KR101603108B1 - Method for transmitting a reference signal - Google Patents

Abstract

The present invention relates to a wireless communication system. Specifically, the present invention provides a method for transmitting a reference signal in a wireless communication system, comprising: generating a subframe including a plurality of PHICH (Physical Hybrid-ARQ Indicator CHannel) groups; Assigning a reference signal to one or more specific PHICH groups; And transmitting the sub-frame.

Description

[0001] METHOD FOR TRANSMITTING A REFERENCE SIGNAL [0002]

The present invention relates to a wireless communication system. The present invention relates to a wireless communication system supporting at least one of SC-FDMA, MC-FDMA and OFDMA. Specifically, the present invention relates to a method for transmitting a reference signal in a wireless communication system.

A 3rd Generation Partnership Project (3GPP) wireless communication system based on Wideband Code Division Multiple Access (WCDMA) radio access technology is widely deployed all over the world. HSDPA (High Speed Downlink Packet Access), which can be defined as the first evolutionary phase of WCDMA, provides 3GPP with highly competitive wireless access technology in the mid-term future.

There is E-UMTS to provide high competitiveness in the long term future. E-UMTS is a system that evolved from existing WCDMA UMTS and is being standardized in 3GPP. E-UMTS is also called Long Term Evolution (LTE) system. For details of the technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of "3rd Generation Partnership Project (Technical Specification Group Radio Access Network)" respectively.

The E-UMTS is largely composed of an Access Gateway (AG) located at the end of a User Equipment (UE), a base station and a network (E-UTRAN) and connected to an external network. Typically, a base station may simultaneously transmit multiple data streams for broadcast services, multicast services, and / or unicast services. In the LTE system, Orthogonal Frequency Divisional Multiplexing (OFDM) and Multi-input Multi-out (MIMO) are used to downlink various services.

OFDM represents a high-speed data downlink access system. The advantage of OFDM is the high spectral efficiency that the entire spectrum allocated can be used by all base stations. In OFDM modulation, a transmission band is divided into a plurality of orthogonal subcarriers in the frequency domain and a plurality of symbols in the time domain. Since OFDM divides the transmission band into a plurality of subcarriers, the bandwidth per subcarrier decreases and the modulation time per carrier increases. Since the plurality of subcarriers are transmitted in parallel, the digital data or symbol transmission rate of a specific subcarrier is lower than that of a single carrier.

A multiple input multiple output (MIMO) system is a communication system using a plurality of transmit and receive antennas. The MIMO system can linearly increase the channel capacity without increasing the additional frequency bandwidth as the number of transmit and receive antennas increases. The MIMO technique uses a spatial diversity scheme that can increase transmission reliability using symbols that have passed through various channel paths and a scheme in which each antenna simultaneously transmits a separate data stream using a plurality of transmit antennas, And a spatial multiplexing scheme for increasing the size of the network.

MIMO technology can be roughly divided into open-loop MIMO technology and closed-loop MIMO technology depending on whether channel information is known at a transmitter. In the open-loop MIMO technique, the transmitter does not know the channel information. Examples of the open-loop MIMO technique include per antenna rate control (PARC), per common basis rate control (PCBRC), BLAST, STTC, and random beamforming. On the other hand, in the closed-loop MIMO technique, the transmitter knows the channel information. The performance of the closed-loop MIMO system depends on how accurately the channel information is known. Examples of the closed-loop MIMO technique include per-stream rate control (PSRC), TxAA, and the like.

Channel information means radio channel information (e.g., attenuation, phase shift, or time delay) between a plurality of transmission antennas and a plurality of reception antennas. In the MIMO system, there are various stream paths by a plurality of transmission / reception antenna combinations, and the channel state has a fading characteristic that varies irregularly in the time / frequency domain due to the multipath time delay. Therefore, the transmitting end calculates channel information through channel estimation. The channel estimation is to estimate channel information necessary for restoring a distorted transmission signal. For example, channel estimation refers to estimating the size and reference phase of a carrier wave. That is, the channel estimation is to estimate the frequency response of the radio section or the radio channel.

As a channel estimation method, there is a method of estimating a reference value based on a reference signal (RS) of several base stations using a two-dimensional channel estimator. In this case, RS is a symbol having high output although it does not have actual data in order to help carrier phase synchronization and acquisition of base station information. The transmitting side and the receiving side can perform channel estimation using the RS. The channel estimation by the RS estimates a channel through a symbol commonly known to the transmitting and receiving sides, and restores the data using the estimated values. RS is also referred to as pilot.

MIMO systems support Time Division Duplex (TDD) systems and Frequency Division Duplex (FDD) systems. In a time division duplex (TDD) system, since the forward link transmission and the reverse link transmission are in the same frequency domain, estimation can be made on the forward link channel from the reverse link channel by the reciprocity principle.

As the communication system develops, it adopts a method of achieving the target with minimum cost by improving the performance of the existing system, rather than defining a new system for each communication technique. In particular, in the case of the communication system, since it can affect not only the RF interface of the terminal or the base station but also all the infrastructure, a method of minimizing the change thereof becomes commercially meaningful. In this environment, It is necessary to maintain the characteristics of the image. In particular, the key requirement is to provide the functionality of the new system without compromising the performance of the existing system, which is currently occurring in the LTE / LTE-A relationship. This situation also occurs when IEEE 802.16m or other communication systems are required to guarantee the operation of the legacy system. The basis of the performance improvement is to increase the modulation order, increase the number of antennas, reduce the influence due to interference, etc. In this case, more reference signal (RS) is needed do. In other words, more information can be delivered by providing a device capable of identifying more channel information and distinguishing each signal component. Currently, the LTE Rel-8 is designed to support up to four multiple antennas. On the other hand, LTE-A aims to support up to 8 multiple antennas. However, a normal OFDM based communication system inserts a reference signal at a specific location and performs channel estimation at that location. And the remaining subcarriers are used for data and control channels. In this situation, when working to improve the system in the future, it is not possible to insert an additional reference signal since the flexibility does not already exist.

However, if a specific resource can be reserved to insert a reference signal, it can be used as a resource for a reference signal. For example, if there is a specific resource that is not allocated from the base station in the legacy terminal, it can be utilized as a resource for the reference signal. As a resource having such a possibility, it is possible to consider a channel that can be used for each terminal. For example, the resource allocation channel, the ACK / NACK response channel, and the traffic channels do not affect the existing legacy terminal regardless of how the base station transmits the channel. However, how such a channel can be useful as a reference signal resource depends on the structure of the actual channel.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently transmitting / receiving a reference signal and a signaling method thereof in a wireless communication system having multiple antennas .

Another object of the present invention is to provide a method and a signaling method for efficiently transmitting / receiving a reference signal when the number of multiple antennas is extended.

It is another object of the present invention to provide a method of transmitting / receiving a reference signal with backward compatibility when the number of multiple antennas is extended and a signaling method thereof.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to a first aspect of the present invention, there is provided a method of transmitting a reference signal in a wireless communication system, the method comprising: generating a subframe including a control region and a data region; Assigning a reference signal to a control channel mapped in the control region; And transmitting the sub-frame.

According to a second aspect of the present invention, there is provided a method of processing a reference signal in a wireless communication system, comprising: receiving a subframe including a control region and a data region; Extracting a reference signal from a control channel mapped in the control region; And estimating a channel using the reference signal.

In the first and second aspects, the control channel is configured using resources remaining in the control region allocated with the reference signal for the first antenna group, and a reference signal for the second antenna group is allocated to the control channel . The first antenna group includes first to fourth antennas among eight antennas, and the second antenna group may include fifth to eighth antennas among the eight antennas.

In the first and second aspects, the reference signal may be assigned to the control channel so as to have a certain pattern in the control region.

In the first and second aspects, the reference signal may be transmitted / received for every multiple of subframes or every multiple of a plurality of subframes. In this case, different offsets may be applied to the starting point of the transmission / reception of the reference signal for each of the component carriers.

In the first and second aspects, the reference signal includes reference signals for the fifth to eighth antennas, and the reference signals for the respective antennas include Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), and CDM Code Division Multiplexing). In addition, the reference signals for the respective antennas can be multiplexed in a hybrid form of TDM, FDM and CDM.

In the first and second aspects, the reference signal may be multiplexed using at least one of TDM, FDM and CDM among a plurality of component carriers. Also, the reference signal can be multiplexed in a hybrid form of TDM, FDM, and CDM between a plurality of component carriers.

In the first and second aspects, the control channel includes a PDCCH (Physical Downlink Control CHannel). In this case, the PDCCH is configured in units of CCE (Control Channel Element). Also, the control channel includes a PHICH (Physical Hybrid-ARQ Indicator CHannel). In this case, the PHICH is composed of three REG (Resource Element Group) units.

In the first and second aspects, the reference signal may be a CRI-RS for measuring a cell-specific reference signal (CRS), a channel state information (CSI), or a DM -RS (DeModulation Reference Signal).

According to a third aspect of the present invention, there is provided a method of transmitting a reference signal in a wireless communication system, the method comprising: generating a subframe including a control region and a data region; Signaling information on a control region format of the subframe; And allocating a reference signal in the control area in a predetermined pattern in association with the format of the control area; And transmitting the sub-frame.

According to a fourth aspect of the present invention, there is provided a method of processing a reference signal in a wireless communication system, comprising: receiving a subframe including a control region and a data region; Checking a control area format of the subframe; Extracting a reference signal assigned from the control region in a predetermined pattern in association with the control region format; And estimating a channel using the reference signal.

In the third and fourth aspects, it may further comprise transmitting / receiving setting information indicating the control area format. The method may further include transmitting / receiving information related to the pattern of the reference signal.

In the third and fourth aspects, the control area format can be confirmed through a Physical Control Format Indicator CHannel (PCFICH).

In the third and fourth aspects, the control area format may be fixed constantly for a specific subframe to which the reference signal is assigned. In this case, the size of the control region in the specific subframe to which the reference signal is allocated can be fixed to 3 OFDM symbols.

In the third and fourth aspects, the control area format can be confirmed from parameters for configuring a PHICH (Physical Hybrid-ARQ Indicator CHannel). In this case, the duration of the PHICH in a specific subframe in which the reference signal is set may be fixed to 3 OFDM symbols.

In the third and fourth aspects, the reference signal may be assigned to a control channel mapped in the control region. In this case, the control channel is configured by using the remaining resources to which the reference signals for the first to fourth antennas are allocated in the control region, and at least one of the reference signals for the fifth to eighth antennas Can be assigned.

Here, the reference signals for the fifth to eighth antennas may be multiplexed using at least one of TDM (Time Division Multiplexing), FDM (Frequency Division Multiplexing) and CDM (Code Division Multiplexing). In addition, the reference signals for the respective antennas can be multiplexed in a hybrid form of TDM, FDM and CDM.

In the third and fourth aspects, the reference signal may be multiplexed using at least one of TDM, FDM and CDM among a plurality of component carriers. Also. The reference signal may be multiplexed in a hybrid form of TDM, FDM and CDM among a plurality of component carriers.

In the third and fourth aspects, the control channel may be a Physical Downlink Control Channel (PDCCH) or a Physical Hybrid-ARQ Indicator CHannel (PHICH).

In the third and fourth aspects, the reference signal includes a CRS (Cell-specific Reference Signal) for the fifth to eighth antennas, a CRI-RS for CSI (Channel State Information) measurement among eight antennas, And may be a DM-RS (DeModulation Reference Signal) used for demodulation for the allocated data channel.

According to a fifth aspect of the present invention, there is provided a method of transmitting a reference signal in a wireless communication system, the method comprising: generating a subframe including a plurality of PHICH (Physical Hybrid-ARQ Indicator CHannel) groups; Assigning a reference signal to one or more specific PHICH groups; And transmitting the sub-frame. The step may further include transmitting information for identifying the PHICH resource to which the reference signal is allocated.

According to a sixth aspect of the present invention, there is provided a method of processing a reference signal in a wireless communication system, the method comprising: receiving information for identifying a PHICH resource to which a reference signal is allocated; Receiving a sub-frame including a plurality of PHICH (Physical Hybrid-ARQ Indicator CHannel) groups; Extracting a reference signal from one or more specific PHICH groups based on the control information; And estimating a channel using the reference signal.

In the fifth and sixth aspects, the one or more specific PHICH groups may be selected to be evenly distributed within the system band.

In the fifth and sixth aspects, the one or more specific PHICH groups may be determined by equally spacing physical indexes of the PHICH group or physical indexes of the REGs that make up the PHICH group.

In the fifth and sixth aspects, the reference signal may be allocated using some of the resources of the specific PHICH group.

In the fifth and sixth aspects, the reference signal can be allocated using a continuous PHICH group or a consecutive REG.

In the fifth and sixth aspects, the reference signal includes a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a demodulation reference (DM-RS) Signal). The reference signals for the respective antennas may be multiplexed using at least one of TDM (Time Division Multiplexing), FDM (Frequency Division Multiplexing) and CDM (Code Division Multiplexing). In addition, the reference signals for the respective antennas can be multiplexed in a hybrid form of TDM, FDM and CDM.

In the fifth and sixth aspects, the reference signal may be multiplexed using at least one of TDM, FDM and CDM among a plurality of component carriers. Also, the reference signal can be multiplexed in a hybrid form of TDM, FDM, and CDM between a plurality of component carriers.

In the fifth and sixth aspects, the reference signal may be transmitted / received every cycle corresponding to a multiple of a subframe or a multiple of a plurality of subframes. In this case, different offsets may be applied to the start time of the transmission / reception of the reference signal for each of the component carriers.

According to a seventh aspect of the present invention, there is provided a method of transmitting a reference signal in a wireless communication system, the method comprising: generating a subframe including a PDCCH search space composed of a plurality of CCEs; Assigning a reference signal in the PDCCH search space; And transmitting the sub-frame.

According to an eighth aspect of the present invention, there is provided a method of processing a reference signal in a wireless communication system, comprising: receiving a subframe including a PDCCH search space made up of a plurality of CCEs; Checking a specific CCE to which a reference signal is allocated in the PDCCH search space; Extracting a reference signal from the specific CCE; And estimating a channel using the reference signal.

In the seventh and eighth aspects, the reference signal may be allocated in a CCE set composed of a predetermined number of CCEs.

In the seventh and eighth aspects, the reference signal may be allocated to a UE-common search space in which search is allowed for all terminals in the cell in the PDCCH search space.

In the seventh and eighth aspects, the reference signal may be allocated in remaining space excluding the CCE reserved for a predetermined purpose among the UE-common search space. In this case, the CCE reserved for the predetermined purpose may be associated with a RACH (Random Access CHannel).

In the seventh and eighth aspects, the reference signal for the first antenna group is allocated to the first UE-common search space, and the reference signal for the second antenna group is allocated to the second UE-common search space. In this case, the first antenna group includes first to fourth antennas among eight antennas, and the first antenna group may include fifth to eighth antennas among the eight antennas.

In the seventh and eighth aspects, the reference signal may be allocated to a UE-specific search space which is allowed to search only for a specific terminal in the PDCCH search space. In this case, the reference signal may be allocated to the first or last CCE of the UE-specific search space and one or more CCEs continuous to the CCE. In addition, the reference signal may be allocated to a plurality of CCEs located at equal intervals in the terminal-specific search space.

In the seventh and eighth aspects, the reference signal includes a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a demodulation reference (DM-RS) Signal). The reference signals for the respective antennas may be multiplexed using at least one of TDM (Time Division Multiplexing), FDM (Frequency Division Multiplexing) and CDM (Code Division Multiplexing). In addition, the reference signals for the respective antennas can be multiplexed in a hybrid form of TDM, FDM and CDM.

In the seventh and eighth aspects, the reference signal may be multiplexed using at least one of TDM, FDM and CDM among a plurality of component carriers. Also, the reference signal can be multiplexed in a hybrid form of TDM, FDM, and CDM between a plurality of component carriers.

In the seventh and eighth aspects, the reference signal may be transmitted / received every a plurality of subframes or every multiple periods of a plurality of subframes. In this case, different offsets may be applied to the starting point of the transmission / reception of the reference signal for each of the component carriers.

According to a ninth aspect of the present invention, there is provided a method of transmitting a reference signal in a wireless communication system, the method comprising: generating a subframe including a control region and a data region; Assigning a reference signal to a data channel mapped in the data area in a predetermined pattern; And transmitting the sub-frame.

According to a tenth aspect of the present invention, there is provided a method of processing a reference signal in a wireless communication system, the method comprising: receiving a subframe including a control region and a data region; Extracting a reference signal allocated to a data channel in the data area in a predetermined pattern; And estimating a channel using the reference signal.

In the ninth and tenth aspects, the predetermined pattern to which the reference signal is allocated is one of patterns A-1 to A-8, patterns B-1 to B-4, patterns C-1 to C-16, D-4 pattern, E-1 to E-1 pattern, and P-1 to P-8 patterns may be applied.

In the ninth and tenth aspects, the data channel is configured using resources remaining in the control region allocated with the reference signal for the first antenna group, and a reference signal for the second antenna group is allocated to the data channel . The first antenna group includes first to fourth antennas among eight antennas, and the second antenna group may include fifth to eighth antennas among the eight antennas.

In the ninth and tenth aspects, the reference signal can be transmitted / received for every multiple of subframes or every multiple of a plurality of subframes. In this case, different offsets may be applied to the starting point of the transmission / reception of the reference signal for each of the component carriers.

In the ninth and tenth aspects, the reference signal includes reference signals for the fifth to eighth antennas, and the reference signals for the respective antennas include Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), and CDM Code Division Multiplexing). In addition, the reference signals for the respective antennas can be multiplexed in a hybrid form of TDM, FDM and CDM.

In the ninth and tenth aspects, the reference signal may be multiplexed using at least one of TDM, FDM and CDM among a plurality of component carriers. Also, the reference signal can be multiplexed in a hybrid form of TDM, FDM, and CDM between a plurality of component carriers.

In the ninth and tenth aspects, the data channel includes a Physical Downlink Shared CHannel (PDSCH).

In the ninth and tenth aspects, the reference signal may be a CRI-RS for measuring a cell-specific reference signal (CRS), a channel state information (CSI), or a DM -RS (DeModulation Reference Signal).

According to the embodiments of the present invention, the following effects are obtained.

First, in a wireless communication system having multiple antennas, it is possible to efficiently transmit / receive a reference signal and to perform signaling on the reference signal.

Second, when the number of multiple antennas is extended, the reference signal can be efficiently transmitted / received and signaling can be performed.

Third, when the number of multiple antennas is extended, a reference signal can be transmitted / received while having signal strength, and signaling for the reference signal can be performed.

Fourth, it is possible to efficiently transmit / receive a reference signal and perform signaling on the reference signal in environments where terminals having different capabilities coexist.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

The structure, operation and other features of the present invention can be easily understood by the preferred embodiments of the present invention described with reference to the accompanying drawings. The embodiments described below are examples in which technical features of the present invention are applied to a wireless communication system. Preferably, the wireless communication system may support at least one of an SC-FDMA scheme, an MC-FDMA scheme, and an OFDMA scheme. Hereinafter, a method of allocating an additional reference signal through various channels will be exemplified. Although the present specification describes the 3GPP LTE channel as an example, the present example can be applied to a control channel of IEEE 802.16 (or a revision version thereof) or a reference signal resource allocation method using a control channel of another system.

Abbreviations used herein are as follows.

RE: Resource element

REG: Resource element group

CCE: Control channel element

CDD: Cyclic delay diversity

RS: Reference signal

CRS: a cell specific reference signal or a cell common reference signal,

CSI-RS: Channel state information reference signal

DM-RS: Demodulation reference signal for data channel demodulation

MIMO: Multi-input multi-output

PBCH: Physical broadcast channel

PCFICH: Physical control format indicator channel.

PDCCH: Physical downlink control channel

PDSCH: Physical downlink shared channel

PHICH: Physical H-ARQ indicator channel

PMCH: Physical multicast channel

PRACH: Physical random access channel

PUCCH: Physical uplink control channel

PUSCH: Physical uplink shared channel

1 shows a structure of a radio frame used in 3GPP LTE.

Referring to FIG. 1, a radio frame has a length of 10ms (327200 占 퐏) and is composed of 10 equal-sized subframes. Each subframe is 1 ms long and consists of two slots. Each slot has a length of 0.5 ms (15360 占 퐏). Here, Ts represents the sampling time, and is represented by Ts = 1 / (15 kHz x 2048) = 3.2552 x 10 ^-8 (about 33 ns). A slot includes a plurality of OFDM symbols in a time domain and a plurality of resource blocks in a frequency domain. A TTI (Transmission Time Interval), which is a unit time at which data is transmitted, may be defined in units of one or more subframes. The structure of the radio frame is merely an example, and the number of subframes included in a radio frame, the number of slots included in a subframe, and the number of OFDM symbols included in a slot can be variously changed.

2 shows a resource grid for a downlink slot.

OFDM 심볼을 포함하고 주파수 영역에서

자원블록을 포함한다. 각각의 자원블록이

부반송파를 포함하므로 하향링크 슬롯은 주파수 영역에서

×

부반송파를 포함한다. 도 2는 하향링크 슬롯이 7 OFDM 심볼을 포함하고 자원블록이 12 부반송파를 포함하는 것으로 예시하고 있지만 이로 제한되는 것은 아니다. 예를 들어, 하향링크 슬롯에 포함되는 OFDM 심볼의 개수는 순환전치(Cyclic Prefix; CP)의 길이에 따라 변형될 수 있다. 자원 그리드 상의 각 요소를 자원요소(resource element)라 하고, 하나의 OFDM 심볼 인덱스 및 하나의 부반송파 인덱스로 지시된다. 하나의 자원블록은

×

자원요소로 구성되어 있다. 하향링크 슬롯에 포함되는 자원블록의 수 (

)은 셀에서 설정되는 하향링크 전송 대역폭(bandwidth)에 종속한다.Referring to FIG. 2,

OFDM symbols, and in the frequency domain

Resource block. Each resource block

Since the sub-carrier includes the sub-carrier, the down-

×

Subcarriers. 2 illustrates that the downlink slot includes 7 OFDM symbols and the resource block includes 12 subcarriers, but the present invention is not limited thereto. For example, the number of OFDM symbols included in the downlink slot may be modified according to the length of a cyclic prefix (CP). Each element on the resource grid is referred to as a resource element, indicated by one OFDM symbol index and one subcarrier index. One resource block

×

It consists of resource elements. The number of resource blocks included in the downlink slot (

) Is dependent on the downlink transmission bandwidth set in the cell.

3 shows a structure of a downlink radio frame.

Referring to FIG. 3, a downlink radio frame includes 10 subframes having an equal length. Each subframe includes an L1 / L2 control region (Layer 1 / Layer 2 control region) and a data region (data region). Unless specifically stated otherwise in the following description, the L1 / L2 control region is referred to simply as a control region. The control region starts from the first OFDM symbol of the subframe and includes one or more OFDM symbols. The size of the control area can be set independently for each subframe. The control area is used to transmit the L1 / L2 control signal. To this end, control channels such as PCFICH, PHICH, PDCCH, etc. are allocated to the control area. Meanwhile, the data area is used to transmit downlink traffic. A PDSCH is assigned to the data area.

4 shows a control channel allocated to a downlink subframe.

Referring to FIG. 4, a subframe is composed of 14 OFDM symbols. The first to third OFDM symbols are used as a control region and the remaining 13 to 11 OFDM symbols are used as a data region according to the number of OFDM symbols for the control region set by the PCFICH among the subframes. In the figure, R1 to R4 represent RSs for antennas 0 to 3. The RS is fixed in a constant pattern in the subframe regardless of the control region and the data region. The control channel is allocated to a resource to which the RS is not allocated in the control region, and the traffic channel is also allocated to the resource to which the RS is not allocated in the data region. Control channels allocated to the control area include PCFICH, PHICH, and PDCCH.

The PCFICH informs the UE of the number of OFDM symbols used in the PDCCH for each subframe as a physical control format indicator channel. The PCFICH is located in the first OFDM symbol and is set prior to the PHICH and PDCCH. The PCFICH is composed of four REGs, and each REG is distributed in the control area based on the cell ID. One REG consists of four REs. The structure of REG will be described in more detail later with reference to Fig. PCFICH indicates a value of 1 to 3 and is modulated by Quadrature Phase Shift Keying (QPSK).

Table 1 illustrates the resource mapping relationship of the PCFICH according to the cell ID.

PHICH is used as a physical H-ARQ indicator channel to carry H-ARQ ACK / NACK for uplink transmission. The PHICH consists of three REGs and is cell-specific scrambled. The resource mapping of the PHICH will be described in detail later with reference to FIG. The ACK / NACK is indicated by 1 bit, spread with SF (spreading factor) = 4, and is repeated 3 times. A plurality of PHICHs can be mapped to the same resource. The PHICH is modulated with binary phase shift keying (BPSK).

The PDCCH is allocated to the first n OFDM symbols of the subframe as a physical downlink control channel. Here, n is an integer of 1 or more and is indicated by the PCFICH. The PDCCH is allocated in units of CCEs, and one CCE includes nine REGs. The PDCCH indicates information related to resource allocation of a paging channel (PCH) and a downlink-shared channel (DL-SCH), an uplink scheduling grant, H-ARQ information, and the like. A paging channel (PCH) and a downlink-shared channel (DL-SCH) are transmitted through the PDSCH. Therefore, the BS and the MS generally transmit and receive data via the PDSCH, except for a specific control signal or specific service data. PDSCH data is transmitted to a terminal (one or a plurality of terminals), and information on how the terminals receive and decode PDSCH data is included in the PDCCH and transmitted. For example, if a particular PDCCH is CRC masked with an RNTI (Radio Network Temporary Identity) of "A ", transmission format information (e.g., For example, a transport block size, a modulation scheme, coding information, etc.) is transmitted through a specific subframe. In this case, one or more UEs in the corresponding cell monitor the PDCCH using the RNTI information it has, and if there is more than one UE having an "A" RNTI, the UEs receive the PDCCH, And receives the PDSCH indicated by "B" and "C"

5 (a) and 5 (b) show resource units used to configure the control channel.

FIG. 5A shows a case where the number of transmission antennas is 1 or 2, and FIG. 5B shows a case where there are 4 transmission antennas. Only the RS pattern is different according to the number of transmission antennas, and the setting method of the resource unit related to the control channel is the same. Referring to FIGS. 5A and 5B, the resource unit for the control channel is REG. REG consists of four neighboring resource elements except RS. The REG is shown in bold lines in the drawings. PCFICH and PHICH include four REGs and three REGs, respectively. The PDCCH is configured in CCE units, and one CCE includes nine REGs. Although the REGs constituting the CCE are illustrated as neighboring to each other, they may be distributed to nine REGs constituting the CCE.

6 shows an example in which the PHICH is allocated in the control region.

The assignment of the PHICH is affected by the PCFICH. The PCFICH is transmitted using four REGs at equal intervals in which the entire subcarrier of the first OFDM symbol is divided into four equal parts, as shown in Table 1, according to the cell ID. The PHICH is defined for the REG to which the PCFICH is allocated and the remaining. For one or more OFDM symbols set by the PHICH duration, a PHICH group is allocated consecutively at a specific starting position by dividing the remaining REGs except RS and PCFICH (first OFDM symbol) on each OFDM symbols .

Referring to FIG. 6, it is divided into three PHICH allocation periods in the frequency domain, and PHICH groups are consecutively allocated in each allocation period. The same numbers in the figure indicate that they belong to the same PHICH group. Each PHICH group consists of three REGs spaced from each other. The PHICH period is limited by the maximum size of the control region, and the PHICH period corresponds to one to three OFDM symbols. When a plurality of OFDM symbols are used for the PHICH, REGs belonging to the same PHICH group for time diversity are transmitted using different OFDM symbols. Also, when the PHICH is transmitted through multiple antennas, REGs belonging to the same PHICH group for spatial diversity are transmitted through different antenna sets, and each antenna set includes two antennas.

7 (a) and (b) illustrate a method of transmitting and receiving a multi-band radio frequency signal.

7A and 7B, one MAC layer in a transmitter and a receiver can manage a plurality of carriers in order to efficiently use multi-carriers. At this time, in order to effectively transmit and receive the multicarrier, it is assumed that both the transmitting end and the receiving end can transmit and receive the multi-carrier. At this time, frequency carriers (FCs) managed in one MAC layer need not be adjacent to each other, so they are flexible in terms of resource management. That is, both Contiguous Aggregation and Non-contiguous Aggregation are possible.

PHY0, PHY1, .. PHY n-2, and PHY n-1 represent multiple bands, and each band may have a frequency allocation band (FA) size allocated for a specific service according to a predetermined frequency policy. For example, PHY0 (RF carrier 0) may have a size of a frequency band allocated for general FM radio broadcasting, and PHY1 (RF carrier 1) may have a frequency band size allocated for mobile communication.

As described above, each frequency band may have different frequency band sizes depending on the respective frequency band characteristics, but in the following description, it is assumed that each frequency band FA has a size of A [MHz] for convenience of explanation. In addition, each frequency allocation band may be represented by a carrier frequency for use of the baseband signal in each frequency band. Hereinafter, each frequency allocation band is referred to as a "carrier frequency band" The representative is simply referred to as "carrier ". In addition, as in the 3GPP LTE-A recently, the above-described carrier wave can be referred to as a "component carrier" in order to distinguish it from a subcarrier used in a multi-carrier scheme. In this regard, the "multi-band" scheme described above may be referred to as a "multi-carrier" scheme or a "carrier aggregation" scheme.

In order to transmit a signal through multiple bands as shown in FIG. 7 (a) and to receive signals through multiple bands as shown in FIG. 7 (b), all transmitters / receivers include an RF module for transmitting and receiving signals in multiple bands . 7A and 7B, the configuration of the "MAC" is determined by the base station irrespective of DL and UL. In short, the "multi-band" scheme is a scheme in which a MAC entity (hereinafter simply referred to as "MAC" in the absence of confusion) manages / operates a plurality of radio frequency (RF) Is transmitted / received. In addition, the RF carriers managed in one MAC need not be contiguous with each other. Thus, the "multi-band" scheme can make resource management more flexible.

FIG. 8 illustrates a method of allocating frequencies in a multi-carrier system.

Referring to FIG. 8, FA 0 to FA 7 can be managed by RF 0 to 7, respectively. In FIG. 8, it is assumed that FA 0, FA 2, FA 3, FA 6, and FA 7 are already allocated to existing specific communication services. In this case, the available RF 1 (FA 1), RF 4 (FA 4) and RF 5 (FA 5) can be effectively managed by one MAC (MAC # 5). Here, since the RF carriers constituting one MAC may not be adjacent to each other as described above, frequency resources can be more effectively managed.

FIG. 9 illustrates a scenario in which communication is performed between one base station and a plurality of terminals in a multi-band supporting method. For the sake of convenience, the downlink is used as an example.

Referring to FIG. 9, it is assumed that signals relating to terminals 0, 1, and 2 are multiplexed. The base station 0 can transmit a signal through a frequency band managed by a carrier of RF 0 and RF 1. It is also assumed that the terminal 0 has a capability of receiving only RF 0, the terminal 1 can receive both RF 0 and RF 1, and the terminal 2 can receive both RF 0, RF 1 and RF 2 . In this case, the base station 0 multiplexes signals relating to terminal 0 only to RF 0, and signals relating to terminals 1 and 2 to RF 0 and RF 1. On the other hand, since the base station transmits only RF 0 and RF 1, the terminal 2 can not receive signals through RF 2.

One embodiment of the present invention relates to a method for downlink transmission of RSs when the number of transmit antennas is extended to M (> N) in a conventional N private system. RS may be a CSI-RS for measuring a cell-specific reference signal (CRS), a channel state information (CSI), or a DM-RS (DeModulation Reference Signal) used for demodulating a data channel allocated to each user. LTE Rel-8 assumes that the number of downlink antennas is 4 (= N). Therefore, the LTE Rel-8 terminal can recognize up to four antennas. On the other hand, in LTE-A, the number of antennas used for downlink transmission is considered to be extended to 8 (= M). It should be noted that an embodiment of the present invention to be described later is exemplified by using LTE-A, but can be applied to the same principle in a system using any MIMO technique that satisfies a condition of M >

In the above environment, LTE-Rel-8 terminals capable of recognizing only the existing 4 (= N) transmit antennas and LTE-8 capable of recognizing 8 (= M) A terminals coexist. In this case, in addition to the reference signals for supporting the existing N antennas, a reference signal for supporting additional 4 (= M-N) antennas should be transmitted. In this case, it is necessary to efficiently transmit data and reference signals in an environment where an LTE-A terminal that recognizes eight antennas is added to an LTE Rel-8 terminal that recognizes only four existing antennas without additional signaling. In order to support the MIMO method for 8 transmit antennas (antenna numbers 0 to 7) in the downlink, it is necessary to measure and estimate channel information for 8 transmit antennas. At the same time, the present 3GPP LTE Rel- Methods are needed to maintain backward compatibility. In order to support the MIMO method for eight transmit antennas (antenna numbers 0 to 7) in the downlink for each component carrier under a system considering a carrier set of single and multi-carrier situations such as LTE-A, It is necessary to measure channel information for eight transmission antennas.

Therefore, the embodiment of the present invention proposes a reference signal transmission method for supporting eight transmission antennas that can satisfy such a requirement. More particularly, the present invention proposes a method for performing channel measurements experienced by eight transmit antennas by transmitting CRS and / or CSI-RS for channel dependent scheduling. The proposed method can be used equally to transmit DM-RS.

LTE Rel-8 defines antenna port 5 to be used in a closed loop rank 1 transmission mode. Therefore, if the antenna port number is defined in the same manner as the current LTE Rel-8, four newly considered antennas (i.e., antennas 4 to 7) are considered as antenna port numbers 6 to 9 (R6 to R9) . R6 to R9, which are considered as antenna port numbers, may be used as a definition of a rank or a layer at the time of MIMO transmission other than an antenna port. In the detailed description given below, the antenna port number can be defined as a rank number or a layer number.

In order to keep the maximum overhead below 15% when transmitting RS, LTE Rel-8 defines the number of RSs included in one resource block as Table 2.

Antenna port
0
One
2
3
# of RS
8
8
4
4

Referring to Table 2, LTE Rel-8 defines 8, 8, 4, and 4 RSs for antenna ports 0-4. Since the number of RSs for antenna ports 2 and 3 is four, if the LTE-A system supports antenna ports 6 to 9 additionally, the number of RSs for additional antenna ports 6 to 9 should be limited to four Can be considered. As the number of RSs increases, accurate channel estimation is possible. However, in the LTE Rel-8 environment in which four antennas are supported, RSs of antenna ports 2-3 are limited to four, so it may be desirable to have the same limitations on the additional antennas Because.

Hereinafter, a method of transmitting RS (R6 to R9) for antenna ports 6 to 9 will be specifically described with reference to the drawings. For convenience, R6 to R9 are referred to as additional RSs. In this specification, RS may be CRS, CSI-RS or DM-RS.

Example 1: Transmission of RS using PDCCH

인 검색 공간

는 PDCCH 후보들의 세트로 정의된다. 검색 공간

에서 PDCCH 후보에 해당하는 CCEs는 하기 식과 같이 정의된다.In the case of the PDCCH, the channel ID and the terminal ID are designed to be associated with each other. That is, the position of a terminal to be searched in one radio frame is determined according to the size of a predetermined PDCCH (LTE Rel-8 is 0 to 3 OFDM symbols). The set of PDCCH candidates to be searched is defined as a search space. Aggregation level

Search space

Is defined as a set of PDCCH candidates. Search space

The CCEs corresponding to the PDCCH candidates are defined as follows.

는 뒤에서 정의되고,

이고

이다.

은 주어진 검색 공간 내에서 모니터 해야 하는 PDCCH 후보의 수이다.From here,

Is defined later,

ego

to be.

Is the number of PDCCH candidates that should be monitored within a given search space.

The terminal must monitor one common search space at aggregation levels 4 and 8 and monitor the terminal-specific search space at aggregation levels 1, 2, 4, and 8. The common and terminal-specific search spaces may overlap.

Table 3 shows examples of search spaces that the terminal should monitor.

는 집합 레벨 L=4 및 L=8에 대하여 0으로 세팅된다. 집합 레벨

에서의 단말-특정 공간

에 대하여,

는 다음과 같다.For the common search space,

Is set to zero for the set level L = 4 and L = 8. Set level

The terminal-specific space

about,

Is as follows.

이고,

이며,

이다.From here,

ego,

Lt;

to be.

As described above, the space to be searched by the terminal is divided into two types. One is a common search space that all terminals must search, and the other is a terminal-specific space. Therefore, when using the CCE, which is the resource of the PDCCH, as the RS resource, both spaces can be considered.

1. When using common search space: When using CCE in common search space, it is the same as using some of the space that all terminals search. However, depending on the definition of the aggregation level, for example, if L = 4 is used, it is preferable to use all the CCEs. Because the rest of the CCE can not be used for other purposes, it is a good idea to just use four CCEs. In this case, it is preferable to use a common search space index that does not overlap with the RACH response channel. When the legacy terminal transmits a signal using the RACH, the common search space index of the corresponding PDCCH is already fixed, and therefore, it should be allocated. Therefore, if the RACH or a specific response falls through the common search space, the collision should be controlled such that no other RS is transmitted at a position where the legacy terminal should wait for a response. Thus, when assigning RS resources in a common search space, fixing a specific resource, or defining a common search space to be used for a specific pattern (such as specifying a cycle or [5, 10, 20, 40 ms] And if you use it's indexes. In order to solve the problem of insufficient CCE resources in the common search space when allocating the CCEs for RS transmission in the common search space, the range of the CCE heat of the common search space dedicated for the LTE-A terminal is changed from the existing CCE indexes # 0 to # (CCE) indexes # 0 to # 15 among the CCE indices of this range are set to LTE Rel-8 and LTE-A PDCCHs carrying information to be commonly received by the UEs or information to be commonly received by the LTE-A UEs or information to be commonly received by the LTE Rel-8 UEs are transmitted and the CCE index # 16 to the CCE index # (N-1) CCEs of the LTE-A UEs can transmit PDCCHs (or CCEs) used for RSs to be received by the LTE-A UEs and PDCCHs that are commonly received by the LTE-A UEs. In this case, the LTE-A terminals recognize the CCE index #N as a terminal-specific search space and perform blind decoding, and the LTE Rel-8 terminals recognize the CCE index # 16 as a terminal-specific search space and perform blind decoding. The PDCCH to be transmitted to the LTE UEs in order to support the UEs may not allocate the CCE index # 16 to the CCE index # (N-1) from the BS scheduler. In this case, the value of N to be set may be set to an arbitrary value of one unit of CCE or to a value of a multiple of 2, 4, or 8 in consideration of the CCE aggregation level.

2. In the case of using the UE-specific search space: In this case, since the position of the PDCCH used by the UE changes in every subframe, a certain number of CCEs are used as a whole according to the aggregate level, It is desirable to set different for each subframe. For example, as described above, since the location of the PDCCH to be searched by each terminal is designated as Y_k and changed according to the subframe index k, it is preferable that the allocation of the CCE is set to a value corresponding to the specific terminal ID. And the number of CCEs to be used in it can be defined as a multiple of one of the possible values of the aggregate level. That is, when a large number of RSs is not required, a CCE can be allocated by setting the number of used CCEs to 1 and designating a specific terminal ID. If a large number of RS resources are needed, it can be used by setting the number of CCEs used as a multiple of one of the aggregate level possible values greater than one. The actual position of the CCE used at this time can be used by using the CCE consecutively with the first or last CCE of the search space, or at regular intervals within the search space. In addition to selecting the CCEs corresponding to a specific ID when assigning the actual RS resources, one or more of the multiple IDs and the set level can be used. For example, if the aggregation level is not set, the CCE reservation can be performed by arranging the aggregation level and the terminal combination. If the aggregation level is determined, the CCE reservation can be performed by only the terminal ID combination. The reservation using the plurality of terminal IDs has the advantage of reducing the number of IDs allocated to the actual terminals by distributing the decrease in the search space experienced by the specific terminals, and making it possible to use all the terminal IDs.

When the CCE is allocated on the basis of the search space as described above, the CCE (s) used to avoid unnecessarily increasing the number of times of blind decoding by the terminal is located at the end of the terminal-specific search space or the CCE If it is located in the common search space, it can be located at the end of the search space or can be located from the CCE index # 0 which is the start point of the terminal search space. For example, for a common search space, if CCEs with L = 4 are to be reused as RS resources, then the preferred space should be the logical CCE indexes 12-15 (0 base). However, there is no need to use the last of the search space as a way to allocate RS resources in the CCE. In particular, in the case of terminal-specific, one terminal CCE overlaps with the CCE search space of another terminal, and since the start position thereof is set at random, there is no gain by assigning the location of a specific CCE to the RS resource. That is, unlike the above scheme, the CCE index positions other than the beginning and end of the UE-specific search space can be arbitrarily set.

In the LTE Rel-8, the CCE of the PDCCH is spread to all or some of the frequency bands using a block interleaver. There are three cases in which the CCE spreads to all bands. First, CCE can be allocated to all bands within each component carrier. Second, CCE can be allocated to all bands including all component carriers. Third, CCE can be allocated through spreading among some component carriers. In the case where the CCE is spread in a partial frequency band, it is possible to consider allocation to a partial band within each component carrier. In order to measure the channel state of the full band or the partial frequency band defined here, a specific CCE is reserved on each component carrier and used as an RS for antennas 4 to 7. Thus, legacy LTE Rel- it is possible to simultaneously perform eight transmission antenna channel state measurement while maintaining backward compatibility.

Also, in some component carriers, it is possible to use all CCEs or all REGs in the area allocated for the PDCCH for the RS. Considering that PHICH resources in each component carrier are allocated to each region of the system band which is equally divided into three equal parts, the PHICH of the specific component carrier can be used to send the RS to the entire band of the specific component carrier.

10 illustrates a method of spreading and allocating RSs within a component carrier. FIG. 10 is an implementation example of a first method of spreading and allocating a full-band CCE.

Referring to FIG. 10, a CCE for RS for antennas # 4 to # 7 is reserved in advance on each component carrier. The CCE for LTE-A and the CCE for LTE Rel-8 are processed by a block interleaver defined for each component carrier, so that RS can be spread and allocated in each component carrier.

11 illustrates a method of spreading and allocating RSs to all component carriers. FIG. 11 is an implementation example of a second method of spreading and allocating a CCE to all bands.

Referring to FIG. 11, a CCE for RS for antennas 4 to 7 is reserved in advance of component carriers, and the CCE is spread to all bands. Thereafter, the CCE reserved for LTE-A and the CCE for LTE Rel-8 are processed by a block interleaver defined for each component carrier, so that RS can be spread and allocated to all component carriers.

FIG. 12-13 shows an example of assignment of RSs for antennas # 4 to # 7 to the CCE.

If the CCE is reserved for RS, the RS can be transmitted using only a part of the reserved CCEs. If interference suppression is required (e. G., CoMP or inter-cell interference), consecutive CCEs can be allocated to RS resources and the RS sequence can be configured via CDM over multiple subcarriers on the corresponding CCE resources. 12 and 13 show examples of a method of transmitting RS with CDM and FDM for CCE. FIG. 12 shows a case where a CCE is allocated and a sequence is spread and transmitted to one or more REGs. 13 shows a case where subcarriers of the CCE are utilized as respective RS resources. Regardless of the multiplexing scheme, the subcarriers used for each RS resource can be used as an RS for the same layer / codeword / rank / antenna and can be duplicated. Although the REGs constituting the PHICH are shown as continuous for the sake of convenience in the drawings, each REG may be allocated in a distributed manner in the system band.

In a situation where the multi-carrier is considered, the transmission period of information on the channel state of the downlink according to each component carrier and the transmission antenna can be adjusted in units of subframes. Therefore, the transmission period of RS for antennas 4 to 7 may be a multiple of N (> = 1) [ms]. For example, the transmission period of RS may be a multiple of 1 ms, a multiple of 2 ms, a multiple of 5 ms, a multiple of 10 ms, a multiple of 20 ms, and so on.

14 shows an example of allocating RSs among component carriers using a TDM (Time Division Multiplexing) scheme.

Referring to FIG. 14, RSs for antennas # 4 to # 7 transmitted through the reserved CCE of the PDCCH are transmitted in units of subframes or subframes for each of the component carriers. On the other hand, different type offsets are applied between each component carrier. The time offset can be given in OFDM symbol units or subframe units. Preferably, the time offset may be given in units of subframes. That is, in each component carrier, additional RSs are transmitted with a fixed period and the component carriers are transmitted in a time division multiplexing (TDM) manner using a time offset. In this case, the RS overhead can be prevented from linearly increasing in proportion to the number of component carriers.

When an RS for antennas 4 to 7 is additionally allocated to each component carrier, hopping between subframes can be considered. It is possible to measure only the channel state of a partial frequency band in one subframe by performing hopping to different bands according to a subframe index or a component carrier index. Accordingly, channel quality measurement Can be performed.

15 shows an example of allocating RSs among component carriers using a frequency division multiplexing (FDM) scheme.

Referring to FIG. 15, RSs for antennas # 4 through # 7 may be assigned to different frequency positions in the form of FDM between component carriers in order to enable multiplexing by component carriers. By allocating different CCE indexes for each component carrier, it is possible to allocate them in FDM form among the component carriers. In addition, by allocating reserved CCE indices to allocate RSs for antennas 4 to 7 for each subframe index or slot, FDM multiplexing can be performed in another form.

 If the reserved CCEs that can be allocated are limited, more CCEs may be allocated to specific component carriers by adjusting the overhead for each component carrier, thereby increasing the density of the RSs and lowering the density of the RSs on the specific component carriers. In addition, a reserved CCE is allocated to each component carrier to maintain a low RS density at a certain level, and the position of OFDM symbols and subcarriers in the PDCCH may be changed according to TDM or FDM on a specific component carrier or index of each subframe So that additional reserved CCEs can be allocated in the form of hybrid TDM and FDM. 14 and 15, in the case where RSs are arranged in each component carrier at a constant cycle, at positions other than the positions where high density or RSs allocated at predetermined densities by the system appear, signaling by the system further lowers Additional RSs can be inserted to have a higher density. In this case, there is an advantage that deterioration of the system performance due to the Doppler effect, which is a channel change in the time-domain, can be reduced. Also, the RS resources used by each antenna may be swapped between each other, and the pattern thereof may take a form dependent on a subframe or a slot.

16 illustrates a method of allocating RSs by code division multiplexing (CDM) to the same time and frequency locations among the component carriers.

Referring to FIG. 16, RSs for antennas 4 to 7 are allocated at the same time and subcarrier positions in a component carrier band for each component carrier, and different sequences are used according to a component carrier index. The location of the resource where the RS sequence overlaps with the CDM can be over the entire band. In addition, the location of the resource in which the RS sequence overlaps with the CDM is provided for each unit (for example, RB or REG unit), so that a channel estimation unit in the coherence BW can be presented. In this case, if the bandwidth of received data is small, it is possible to reduce the disadvantage of estimating all channels of a wide band. At this time, the sequence type can be divided into a basic sequence capable of distinguishing the antennas and a cell-specific sequence configuring the entire band, thereby configuring the entire RS sequence. Here, when component carriers have a configuration in the adjacent form, there is a disadvantage that PAPR / CM can be large when simple repetition is performed using the same sequence between the component carriers. However, when the CDM method is applied, the problem of increasing the PAPR can be overcome. A sequence that may be used in the present embodiment includes a sequence having a low orthogonal sequence or a cross-correlation value. Such a sequence may include, but is not limited to, a pseudo random noise (PN) sequence, a Zadoff-Chu sequence of a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence, a Generalized Chirp-Like (GCL) sequence, and the like.

For example, the RSs of antennas # 4 to # 7 are allocated to the same OFDM symbol and subcarrier positions irrespective of the index of the component carrier for each antenna, and a different PAPR / CM characteristic can be obtained by applying different sequences to RSs for each component carrier. have. As another example, the RSs of antennas # 4 to # 7 are allocated to the same OFDM symbol and subcarrier positions irrespective of the index of the component carrier for each antenna, and a CAZAC sequence is allocated to the RS of a component subcarrier and a CAZAC sequence is allocated to the RS of another component subcarrier. Different cyclic shifts of the sequence can be assigned. As described above, by changing the sequence of the RSs for each component carrier wave, it is possible to have a low PAPR / CM characteristic. In order to solve the problem of increasing the PAPR / CM by repetition by using the same sequence for each component carrier wave for each antenna in the case of allocating RSs for antennas 4 to 7, The problem of increasing the PAPR / CM can be solved by performing phase modulation on the subframe or RS for antennas 4 to 7 as described above (i.e., modulating -1 or +1 for each component carrier or RS portion).

As one embodiment, the following cases can be considered.

P (0) = 1, p (1) = 1 and p (2) = - 1 when N = 3 and the modulated p (n) is binary. P (0) = 1, p (1) = 1, p (2) = 1 and p (3) = - 1 when N = 4 and the modulated p (n) is binary. (1) = 1, p (2) = 1, p (3) = - 1 and p (4) = 1 when N = 5 and the modulated p Lt; / RTI > Here, N denotes the number of component carriers, and p (n) denotes a phase modulation applied to a subframe transmitted by a specific component carrier or an RS for antennas 4 to 7.

Next, a method of performing RS multiplexing within each component is illustrated.

FIG. 17 illustrates a method of multiplexing RSs for 4-7 antennas in a component carrier by the FDM method.

Referring to FIG. 17, RSs can be allocated in an FDM manner by assigning RSs for antennas 4 to 7 to different CCEs in a subframe for orthogonality between antennas. FIG. 17 shows RSs for antennas 4 to 7 in a localized form in order to more easily illustrate FDM multiplexing between antenna ports. However, as an example, the RSs for the different antennas may be allocated in a distributed or staggered manner within a certain band. In addition, although the number of OFDM symbols constituting the PDCCH is assumed to be three, even when the PDCCH is composed of 2 or less or 4 or more OFDM symbols, the RS for the antennas 4 to 7 can be allocated by the FDM scheme have.

FIG. 18 illustrates another method of multiplexing the RSs for 4-7 antennas in a component carrier by the FDM method.

Referring to FIG. 18, an RS for antennas # 4 through # 7 is allocated to different CCEs in a component carrier, and RSs are allocated in an FDM manner, and swapping between different antennas can be performed. FIG. 18 is a diagram for explaining the swapping between the antenna ports 6 and 9 more easily. In FIG. 18, the antenna ports 6 and 7 and the antenna ports 8 and 9 are allocated by paring. However, Swapping cases of some form of pairing can be possible for 6-9. Also, a method of constructing consecutive symbols for the same antenna in consecutive resource units can be considered. For example, in FIG. 18, for R6, R7, R8, and R9, R6 uses the first four, R7 uses all four, and R8 and R9 similarly occupy consecutive subcarriers. Here, the RS blocks of R6, R7, R8, and R9 may have an interlaced form with each other.

FIG. 19 illustrates a method of multiplexing RSs for 4-7 antennas in a component carrier by the CDM method.

Referring to FIG. 19, the RSs for antennas # 4 to # 7 allocated to the PDCCH are allocated to the same CCE irrespective of the antennas, but they can be multiplexed using the CDM scheme by using different sequences for orthogonality between the antennas. A sequence that may be used in the present embodiment includes a sequence having a low orthogonal sequence or a cross-correlation value. Such a sequence may include, but is not limited to, a pseudo random noise (PN) sequence, a Zadoff-Chu sequence of a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence, a Generalized Chirp-Like (GCL) sequence, and the like.

For example, the same OFDM symbol and subcarrier may be allocated to RSs of antennas # 4 to # 7 for each antenna in each component carrier, but different orthogonal sequences may be used. For another example, CAZAC sequences are used for RSs 4 to 7, and CAZAC sequences having different cyclic shifts are used for each antenna, so that orthogonal characteristics can be obtained between RSs of respective antennas.

20 illustrates a method of multiplexing RSs for antennas 4 to 7 in a component carrier by a TDM scheme.

Referring to FIG. 20, it is possible to allocate RSs for antennas # 4 to # 7 in the same component carrier to the same CCE for each subframe, and to perform TDM between different antennas. In the drawing, <R6 and R8> and <R7 and R9> are multiplexed in different subframes by the TDM scheme and the RSs allocated in the same subframe are multiplexed by the FDM scheme for each antenna. This is for illustrative convenience only and the present invention is not limited thereto. For example, the number of RSs per antenna allocated in one subframe may be 1 or 3, and antenna port numbers of RSs allocated together in the same subframe may be variously combined.

FIG. 21 illustrates another method of multiplexing RSs for antennas 4 to 7 in a component carrier by the TDM method.

Referring to FIG. 21, TDM can be performed between different antennas by assigning different CCEs for RSs 4 to 7 in the same component carrier for each subframe. By doing so, the RSs for the antennas 4 to 7 in one component carrier have a multiplexed form using both the TDM scheme and the FDM scheme.

 The method shown in FIGS. 20 and 21 has proposed a method of using TDM between subframes, but this is for convenience of description, and the present invention is not limited thereto. For example, it is also possible to multiplex RSs for antennas 4 to 7 in the form of TDM within an OFDM symbol that the PDCCH can have in one subframe. In addition, a TDM type in which only one RS for one antenna is transmitted in one period in which the RS is transmitted is also possible.

A method of multiplexing RSs for antennas 4 to 7 can be additionally considered. For example, a pre-reserved CCE may be allocated for antennas 4 and 5 in the first subframe, a pre-reserved CCE may be allocated for antennas 6 and 7 in the second subframe, You can alternate between the 4th antenna and the 8th antenna. In addition, an offset can be assigned to each of the component carriers, so that different antennas can be allocated among the component carriers. For example, in the first component carrier, subframes are alternately allocated in order of antennas 4, 5, 6, and 7, and in the order of antennas 5, 6, 7, and 4 in the second component carrier, 6, 7, 4, and 5 antennas, and in the fourth component carrier, the subframes can be alternately allocated in the order of 7, 4, 5, and 6 antennas.

Concrete example  2: PHICH Using RS Transmission of

In order to measure the channel status of the full-band or partial-frequency band, a specific PHICH is reserved on each component carrier and used for CRS for antennas 4 to 7, thereby achieving backward compatibility with legacy LTE Rel- And simultaneously perform channel state measurement of eight transmit antennas.

에 의해 결정되고,

는 PHICH 그룹 번호이고

는 PHICH 그룹 내에서의 직교 시퀀스 인덱스를 나타낸다. PHICH 그룹은 ACK/NACK을 보내는 전송단위로서 서로 이격된 3개의 REG로 구성된다. LTE Rel-8의 프레임 구조 타입 1에서, PHICH 그룹의 개수는 모든 서브프레임에서 일정하며 하기 수학식으로 결정된다.In LTE Rel-8, the PHICH resource is an index pair

Lt; / RTI &gt;

Is the PHICH group number

Represents an orthogonal sequence index in the PHICH group. The PHICH group consists of three REGs separated from each other as transmission units for sending ACK / NACK. In the frame structure type 1 of LTE Rel-8, the number of PHICH groups is constant in all subframes and is determined by the following equation.

는 상위 계층에 의해 지시되고,

은 서브프레임 내 자원블록의 개수를 나타낸다.From here,

Is directed by an upper layer,

Represents the number of resource blocks in a subframe.

According to the value of Ng, the number of PHICH groups can be set from 1/4 to 1/48 of the total number of resource blocks. The index of the PHICH group used by each UE is referred to as a combination of the index value of the resource including the allocation information received by the UE and the uplink RS.

Even if the allocation information is received through the same specific resource, the BS can distinguish resources of the PHICH used by specifying an arbitrary RS in order to distinguish resources. Such a relationship is defined as the following equation.

는 DMRS (demodulation reference signal)를 위한 순환 쉬프트에 매핑되고,

는 PHICH 변조를 위한 확산 인자 사이즈이며,

는 상향링크 자원 할당에서 가장 작은 PRB 인덱스를 나타내고,

는 PHICH 그룹의 개수이며,

는 다음과 같다.From here,

Is mapped to a cyclic shift for a demodulation reference signal (DMRS)

Is the spreading factor size for PHICH modulation,

Represents the smallest PRB index in the uplink resource allocation,

Is the number of PHICH groups,

Is as follows.

과

가 기 설정된 가운데

과

는 기지국 스케줄러가 임의로 지정할 수 있는 자유도가 있다. 따라서, 기지국 스케쥴러는 RS 용으로 사용되는 PHICH 그룹 인덱스들이 지정되 지 않도록

값을 조절하는 목적으로

과

을 임의로 설정할 수 있다. 따라서 기존 레거시 단말의 경우에는 해당 사항을 전혀 파악할 수 없고 동작에 아무런 지장을 받지 않으므로 호환성이 유지된다. 반면 새로운 기능을 갖는 단말의 경우에는 이를 파악해야 한다. 따라서 기지국에서는 RS 자원으로 할당된 PHICH 자원에 대해서 인디케이션을 수행해야 한다. 이를 위해서 기지국은 해당 PHICH 정보를 알려주기 위해서 브로드캐스트 정보 (즉, 시스템 정보)를 통해 어떠한 PHICH 그룹들이 RS 자원으로 예약되었는지 알려줄 수 있다. 예를 들어 다음과 같은 구조로 브로드캐스팅해 줄 수 있다.Therefore, in order to transfer a specific PHICH resource to the RS resource, the BS can adjust the resource to be used by the terminal by referring to the location where the allocation information is located and the RS so that the specific PHICH group is not used. More specifically, in Equation 4 regarding the PHICH group index assignment,

and

With preset

and

Can be arbitrarily designated by the base station scheduler. Therefore, the base station scheduler is configured such that PHICH group indexes used for RS are not specified

For the purpose of adjusting the value

and

Can be arbitrarily set. Therefore, existing legacy terminal can not grasp the relevant information at all and does not interfere with the operation, so compatibility is maintained. On the other hand, if the terminal has a new function, it should be understood. Therefore, the BS must perform indication on the PHICH resource allocated as the RS resource. For this purpose, the base station can inform which PHICH groups are reserved as RS resources through broadcast information (i.e., system information) in order to inform the corresponding PHICH information. For example, you could broadcast it with the following structure.

1. It directly informs the indexes of PHICH group to be used as RS. In this case, the index of the PHICH resource used by the RS is directly informed by the sequence. As an example, you can tell the listing of the index. In another example, the start position (i.e., offset) of the index reserved for the RS and the period in which the indexes used as the RS appear can be informed. As another example, the starting and ending positions of the reserved indexes for the RS can be informed by using the delta offset for the indicated value. As another example, the indexes reserved for RSs can be simply informed through bitmaps.

2. Indicate indirectly the PHICH group to be used as RS. In this case, the base station and the terminal recognize the predetermined PHICH group set as an RS. In this case, the PHICH groups index values that can be used as RSs in the air interface standard are defined (the definition type may have the same structure as the number 1), and the base station has a format that indicates that the corresponding PHICH groups are used. For example, in the LTE-A system, when a set of the corresponding PHICH group is used as an RS, a bit can be defined to notify it. In addition, if a set of PHICH groups is defined in various ways, it has a structure for indicating an index corresponding to a set of groups to be used. If a set of PHICH groups is not utilized for RS, an index for a null set can be defined and informed. When defining an index for a set of PHICH groups, the definition for the set may have a different structure or have the same structure according to the PHICH format.

It is easy to tell whether a PHICH group is used as an RS or not in a certain period (1 TTI, 10 TTI, or 40 TTI units, etc.). In fact, if the configuration related to the above is transmitted over the broadcast channel (BCCH), the period of notifying the setting about the PHICH has the same length as the BCCH. In this case, since the terminal performing the initial access (eg, power-on, handover, etc.) can not know such information about the PHICH associated with the RS, the RS setting of the corresponding cell can be used You can enter a state without it. Therefore, signal generation in the PDCCH or PHICH should be applied from a point in time when the terminal can clearly know the RS setting. That is, when the terminal does not know the RS information at the initial access, it generates and transmits the signal only in the legacy transmission mode. If the terminal finds the RS information, the signal transmission at the PHICH, PDCCH and PUSCH can use additional pilots TxD, precoding, and MIMO mode. In addition, if there is no indication of a specific event, the same setting can be continuously used. The number of PHICH groups that can be used to inform the UE in this way is limited to the RS number in order to make the control channel used as the allocation information available to all UEs. For example, if the number of indexes available for RS is 8, the maximum number of PHICH groups that can be selected and transferred to RS is limited to 8. However, if the physical resources for specific allocation information are unavailable, the maximum number of available resources may increase.

The physical subcarrier resources used by PHICHs in LTE Rel-8 depend on the PCFICH and legacy RS used in the corresponding cell. That is, the order of resource allocation defines RS, and REG is defined through remaining resources excluding the pilot. Each control channel is assigned to this REG as a basic unit. PCFICH is allocated first, and four REGs are assigned to positions defined by the following equation in the first OFDM symbol.

와

는 앞에서 설명한 바와 같고, k는 다음과 같다.From here,

Wow

Is as described above, and k is as follows.

는 물리 계층 셀 ID를 나타낸다.From here,

Represents a physical layer cell ID.

As can be seen from the above equation, the PCFICH is transmitted using four REGs at an equal interval in which the entire subcarrier of the first OFDM symbol is divided into four equal parts, although the starting position is changed according to the cell ID. The PHICH is defined for the remaining REG. For one or more OFDM symbols set by the PHICH duration, the remaining REGs except RS and PCFICH (first OFDM symbol) The PHICH group is allocated consecutively at the location. Therefore, if the resources used in the PHICH in this structure are not evenly distributed over the entire band, the RS may not be uniformly distributed over the entire band. Therefore, it is preferable to increase the number of PHICH groups in order to evenly spread the RS over the entire band. That is, in order to utilize the PHICH as the RS resource, it is reasonable to set Ng = 1 or 2 when determining the number of PHICH groups. In this case, considering the positions of the PCFICH and the legacy RS, it is preferable to select the REGs of the selected PHICH group to be equally spaced in the system band. As a method of selecting a PHICH group index to be used for RS, a method of extracting PHICH logical indexes at equal intervals can be considered. Alternatively, it may be preferable to select physical REG indexes at regular intervals rather than extracting PHICH logical indexes at regular intervals in order to more evenly select PHICHs on physical resources. In consideration of the proposed scheme, the resource index used when the PHICH group is used as the RS resource may be a PHICH logical index, but it can be expressed as a physical index of the REG. In this case, the resources available for PHICH are automatically determined by the PHICH logical index which overlaps the REG index used for RS.

The PHICH reserved for the additional RS of LTE-A can be spread to full-band or partial frequency band using a block interleaver. There are three cases where PHICH spreads to all bands. First, PHICH can be allocated to all bands within each component carrier. Second, the PHICH can be allocated to all bands including all component carriers. Third, the PHICH can be allocated by spreading among some component carriers. The case where the PHICH is spread in a partial frequency band can be considered as a partial band allocation in each component carrier. In order to measure the channel state of the full band or the partial frequency band defined here, a specific PHICH is reserved on each component carrier and used as an RS for antennas 4 to 7. Thus, legacy LTE Rel-8 and anti- it is possible to simultaneously perform channel state measurement of eight transmit antennas while maintaining backward compatibility.

Figure 22 illustrates a method of spreading and allocating RSs within a component carrier. FIG. 22 shows an embodiment of a first method for spreading and allocating the entire band of the PHICH.

Referring to FIG. 22, a PHICH for RS for antennas 4 to 7 is reserved in each component carrier. RSs can be spread and allocated within each component carrier by processing the PHICH reserved for LTE-A and the PHICH for LTE Rel-8 with a block interleaver defined for each component carrier.

23 illustrates a method of spreading and allocating RSs to all component carriers. FIG. 23 shows an embodiment of a second method for spreading and allocating the entire band of the PHICH.

Referring to FIG. 23, PHICHs for RSs for antennas 4 to 7 are reserved in the upper part of the component carriers, and the PHICHs are spread to all bands. After that, the PHICH reserved for LTE-A and the PHICH for LTE Rel-8 are processed by a block interleaver defined for each component carrier, so that RS can be spread and allocated to all component carriers.

24-25 shows an example of assignment of RSs for antennas 4 to 7 to PHICH.

If the PHICH is reserved for RS, the RS can be transmitted using only a part of the reserved PHICHs. If interference suppression is required (e. G., CoMP or inter-cell interference), consecutive PHICHs may be allocated to RS resources, and on the corresponding PHICH resource, the RS sequence may be configured via CDM over several subcarriers. 24 and 25 show examples of a method of transmitting RS with CDM and FDM for PHICH. FIG. 24 shows a case where RS is allocated to the PHICH and the sequence is spread and transmitted to one or more REGs. 25 shows a case where subcarriers of the PHICH are utilized as respective RS resources. Regardless of the multiplexing scheme, the subcarriers used for each RS resource can be used as an RS for the same layer / codeword / antenna and can be duplicated. In the figure, REGs constituting PHICHs are shown as continuous for the sake of convenience, but each REG is distributed and allocated in the system band.

26 shows an example of transmitting RSs of antennas # 4 through # 7 through PHICH.

Referring to FIG. 26, the system band is divided into three parts in relation to the PHICH. Each part represents a PHICH resource allocation area, and each part is assigned one of three REGs belonging to the same PHICH group. In the figure, the same numbers represent REGs belonging to the same PHICH group. The RS for antennas 4 to 7 is allocated to one reserved PHICH group among the PHICH groups. Just as REGs constituting a PHICH group are distributed to three PHICH resource allocation areas, PHICH group resources to which additional RSs are allocated are also distributed to three PHICH resource allocation areas.

27 shows another example of transmitting the RSs of the antennas 4 to 7 through the PHICH.

Referring to FIG. 27, the basic matters are the same as those described in FIG. 26, and therefore, the details are described with reference to FIG. 26 and the foregoing description. Figure 27 further illustrates the transmission of the RS in terms of time when the period of the PHICH includes a plurality of OFDM symbols. The PHICH period is limited by the maximum size of the control region, and the PHICH period corresponds to one to three OFDM symbols. When multiple OFDM symbols are used for the PHICH, the REGs belonging to the same PHICH group for transmit diversity are transmitted on different OFDM symbols. Likewise, the RSs allocated to the PHICH are also transmitted on different OFDM symbols in units of REGs.

In FIGS. 26 and 27, the configuration of the PHICH, the RS allocation, the RS multiplexing between the antennas, and the RS allocation in the case of the multi-carrier are described in detail above, 26 shows only one case for convenience of explanation, but the contents described in connection with the PDCCH can be similarly applied. That is, the contents of FIGS. 14 to 21 exemplified with respect to the PDCCH can be applied to the PHICH in the same or similar manner.

Concrete example  3: Antennas 4 to 7 RS For Signaling

A signaling method related to the RS will be described in detail when the number of transmission antennas is extended from 4 to M (M > 4). For convenience, it is assumed that M = 8, but the present invention is not limited thereto.

28 shows a flowchart for performing signaling for the RSs of the antennas 4-7.

Referring to FIG. 28, the UE determines the format of the L1 / L2 control region in the received subframe (S2810). The control region format may be performed through implicit signaling or explic signaling. In one example, the control area format may be predetermined for a particular subframe. In addition, the control area format may be indicated via a broadcasting channel. In addition, the control area format may be indicated via the PCFICH. In addition, the control area format may be indicated indirectly through information associated with the PHICH. When the control area format is confirmed, the terminal determines an RS pattern for antennas 4 to 7 based on the control area format (S2820). The RS pattern for antennas 4 to 7 may be predetermined or semi-predetermined according to the control area format. Therefore, if necessary, the terminal uses the additional information to determine the RS pattern for antennas 4 to 7. Additional information may be signaled or signaled separately with information regarding the control region format. After the RS pattern is determined, the terminal extracts an RS pattern for the antennas 4 to 7 from the control region of the received subframe (S2830), and estimates the transmission channel from the antennas 4 to 7 using the extracted RS (S2840). Thereafter, the terminal transmits channel estimation results for antennas 4 to 7 to the base station (S2850). The channel estimation result includes, but is not limited to, Channel Quality Indicator (CQI) or Channel State Information (CSI).

The flow chart of FIG. 28 has been illustrated focusing on the RS for antennas 4 to 7. The MS actually receives the RS for antennas 0 to 3 and performs channel estimation. The RSs for the antennas 0 to 3 and the RSs for the antennas 4 to 7 are separately used in the channel estimation, but they may be combined with each other in order to improve the channel estimation performance. 28 is described in the context of a terminal, this is for convenience of explanation, and the corresponding procedure is performed in the same way in the base station. Hereinafter, the signaling with respect to the RSs of the antennas 4 to 7 will be described in more detail.

A. How to find RS for antennas 4 ~ 7

In an LTE-A system using MIMO technology using 8 transmit antennas, RSs for antennas 4 through 7 need not be transmitted in all subframes. Therefore, the UE needs to know the position of the subframe in which the RS exists for the antennas # 4 to # 7. Unless specifically stated otherwise, the following additional RSs refer to RSs for antennas 4 through 7. When the subframe in which the additional RS exists is static, additional RS is fixedly allocated to the specific (Mth) subframe of the radio frame, so no signaling is required. If the position of the subframe in which the RS exists in the Mth subframe to the Lth subframe is changed with a long N (>> 1) radio frame period even if the additional RS is statistically assigned to the subframe, It should be transmitted through system information. When the subframe in which the additional RS exists is semi-static, the additional RS can be allocated to the Mth subframe with a certain N (N> 1) radio frame period through the system information, and the position of the subframe is maintained Can be informed through the configuration information. If a subframe in which additional RSs are dynamically allocated is dynamically allocated, the position of the subframe may be informed through the system information every radio frame. Through the system information, the position of the subframe in which the RS exists can be informed by using the bitmap for the radio frame, or can be informed using the binary information about the position and period of the subframe.

Even if the terminal knows the position of the subframe in which the additional RS is transmitted, more specific location information in which additional RS exists is needed. The location of the additional RS depends on the PCFICH value since it must be compatible with Rel-8. Therefore, the approach may vary depending on whether the PCFICH value needs to be checked.

A-1) How to know RS independently from PCFICH

When transmitting additional RSs for MIMO technology (e.g., spatial multiplexing (SM), transmit diversity (TxD), precoding, beamforming, etc.) at an LTE-A base station, LTE Rel- We propose to use fixed Nc (3 in Rel-8) OFDM symbols as a control resource on the time axis, which is the maximum amount that can be used as a control resource in LTE Rel-8, to ensure backward compatibility. In this case, the RS can be read without looking at the PHICH or PCFICH. However, downlink radio resources may be wasted when necessary control resources are smaller than Nc OFDM symbols.

Alternatively, the LTE Rel-8 is configured to inform the UE of the length information on the OFDM symbol occupied by the PHICH through the BCH. Therefore, when the MIMO technique is supported using 8 transmit antennas, the LTE-A base station sets the length information on the OFDM symbol occupied by the PHICH in the subframe in which the additional RS exists through the BCH to 3. Since the maximum value of the PCFICH is limited to 3 in the LTE Rel-8, if the OFDM symbol length associated with the PHICH is set to 3 on the BCH, the UE can know that the PCFICH is 3 without viewing the PCFICH information. Therefore, the additional RS can be read from the fixed OFDM symbol and subcarrier position without further viewing the control information on the PCFICH. Alternatively, when the control information is additionally allocated in the form of FDM in an RB-dependent manner, the LTE-A base station adds an option to the information on the OFDM symbol length occupied by the PHICH to be informed on the BCH, May be indicated using the PHICH information bits on the BCH.

Alternatively, when RS is transmitted in every subframe or in a constant period, the PCFICH value in a preceding subframe is constantly related to a known PCFICH value. That is, a relation such as 0, +1, -1, +2, -2 can be preset for the PCFICH value used in the previous Ns subframe. It is appropriate that this relation is conveyed to the broadcast information. For example, I'll show you how to set +1. At this time, it should be set as a method of increasing +1 within the maximum PCFICH value. Thus, without decoding information on the PCFICH of the current subframe, it is possible to read the RS from the subcarrier position and the OFDM symbol previously determined according to the PCFICH value of the preceding subframe or known between the terminal and the base station.

Alternatively, we propose a method for assigning RSs for antennas 4 to 7 to fixed OFDM symbols and subcarrier locations.

A method of assigning additional RSs for each OFDM symbol to all of the scheduling bandwidths in a form of distributed allocation (for example, a method of allocating N OFDM symbols with the same spacing, a randomly distributed allocation) ) To a physical allocation unit may be considered. In order to guarantee backwardness in LTE Rel-8, such a method should not cause deterioration in performance of LTE Rel-8 system in multiplexing with CCE, which is the control information allocation unit of LTE Rel-8. When the multiplexing with the CCE degrades the performance of the LTE Rel-8 system, this method, which is considered as a method of independently knowing the RS according to the PCFICH, can be utilized as a method only for LTE-A.

A-2) How to know RS after decoding PCFICH

The LTE-A terminal obtains information on the PCFICH using only up to four antennas. That is, the LTE-A terminal decodes the PCFICH using only the RS used in the LTE Rel-8 system, and can read the preset RS from the fixed OFDM symbol and subcarrier location based on the information obtained from the PCFICH.

B. PCFICH or PHICH  How to determine the RS pattern according to the value

A method for determining a pattern for a specific OFDM symbol and an RS added to a subcarrier position according to the PCFICH / PHICH_len value will be described. Here, PHICH_len is the number of OFDM symbols occupied by the PHICH informed by the BCH. Hereinafter, a method of predetermining an additional RS position for PCFICH / PHICH_len = 1, PCFICH / PHICH_len = 2, and PCFICH / PHICH_len = 3 is presented. A situation may arise where channel estimation via additional RS is first required to decode the PCFICH when the PCFICH is transmitted using eight transmit antennas. To prevent this, the PCFICH transmission can be done in a 2Tx or 4Tx TxD manner using four or two reference signals (meaning RS of 4 antenna ports defined for 4Tx transmission in LTE Rel-8) have. That is, the PCFICH transmission can be performed using the TxD scheme defined in LTE Rel-8 using two or four physical antennas. In addition, the PCFICH transmission can be accomplished via two or four virtual antenna ports by using an antenna virtualization scheme that groups the eight physical antennas into two or four units and transmits the same data and reference signals. Also, considering the backwardness of LTE Rel-8 UEs, the TxD scheme defined in LTE Rel-8 using the RSs of the four antenna ports designated in LTE Rel-8 like the above-described schemes in the entire PDCCH Can be applied.

In addition, when it is assumed that an additional RS is allocated to the CCE of the PDCCH, a specific CCE set index is allocated for PCFICH = 1 for additional RS, a CCE set index different from PCFICH = 1 is allocated for PCFICH = 2, In the case of PCFICH = 3, the RS position can be predetermined by assigning a different CCE set index to PCFICH = 1 and PCFICH = 2. Here, the CCE set index may be a logical index or a physical index. Concretely, according to the PCFICH value such as the CCE set index L for PCFICH = 1, the CCE set index M for PCFICH = 2, the CCE set index N for PCFICH = 3, and so on, RS is different from OFDM symbol and subcarrier You can use the method that is assigned to the resource. Also, as the PCFICH value increases, a method of assigning the RSs with varying density (density) may be considered. That is, as the PCFICH value increases, the RS density can be increased or decreased by increasing or decreasing the set index number of the CCE for allocating the RS. Specifically, the CCE set index L is assigned for PCFICH = 1, the CCE set index L and M are assigned for PCFICH = 2, and the CCE set index L, M and N for PCFICH = CCE. In this manner, as the PCFICH value increases, a new CCE set index can be additionally allocated in addition to the previous CCE set index. Alternatively, when PCFICH = 1, the CCE set index L is allocated. When PCFICH = 2, the CCE set index M and M + 1 are allocated. When PCFICH = 3, N + 1 and N + 2 can also be used.

The above embodiment is an example of a method of determining the RS pattern according to the PCFICH value. The following example is an example of how to determine the RS pattern according to the value of the number of OFDM symbols (PHICH_len) occupied by the PHICH informed by the BCH in the same manner as above. Assuming that an additional RS is allocated to the CCE of the PDCCH, a specific CCE set index is allocated for PHICH_len = 1 for the additional RS, a CCE set index different from that for PCFICH_len = 1 is allocated for the RS for the PCFICH_len = 2 , PCFICH_len = 1, and PCFICH_len = 2 in the case of PCFICH_len = 3, the location for the RS may be predetermined to allocate a different CCE set index. Concretely, according to the PCFICH value such as the CCE set index L for PCFICH_len = 1, the CCE set index M for PCFICH_len = 2, the CCE set index N for PCFICH_len = 3, and the like, RSs are allocated to different OFDM symbols and subcarriers You can use the method that is assigned to the resource. Also, as the PCFICH value increases, a method of assigning the RSs with varying density (density) may be considered. That is, as the PCFICH value increases, the RS density can be increased or decreased by increasing or decreasing the number of set indexes of CCEs for allocating RSs. Specifically, the CCE set index L is assigned for PCFICH_len = 1, the CCE set index L and M are assigned for PCFICH_len = 2, and the CCE set index L, M and N for PCFICH_len = CCE. In this manner, as the PCFICH_len value increases, a new CCE set index can be additionally allocated in addition to the previous CCE set index. Alternatively, when PCFICH_len = 1, a CCE set index L is assigned. When PCFICH_len = 2, CCE set indexes M and M + 1 are allocated. When PCFICH_len = 3, N + 1 and N + 2 can also be used.

The number of CCEs that can be used as RS can be made simple by keeping a certain ratio according to the system BW. For example, the number of CCEs can be increased in proportion to the BW of each system. Specifically, when the system BW is 5 MHz, the number of CCEs is N, the number of CCEs is 2 × N in case of 10 MHz, and the number of CCEs is 4 × N in case of 20 MHz. . As an example, the number of CCEs according to the system BW is not limited to this. Alternatively, a method of using a fixed number of CCEs per system BW may be considered. Specifically, RSs can be allocated using N number of CCEs when the system BW is 5 MHz, M number of CCEs when 10 MHz, and L number of CCEs when 20 MHz.

In addition, it is possible to consider multiple definitions of usable RS patterns. That is, it is possible to consider a plurality of RS patterns in which a CCE index is preset, using any one of the RS patterns. By defining several RS patterns, it is possible to prevent RS from colliding between cells or sectors. But are not limited to, the following examples.

Pattern 1-1
PCFICH = 1 => CCE set index = L;
PCFICH = 2 => CCE set index = L + 1; And PCFICH = 3 => CCE set index = L + 2

Patterns 1-2
PCFICH = 1 => CCE set index = M;
PCFICH = 2 => CCE set index = M + 1; And PCFICH = 3 => CCE set index = M + 2

Patterns 1-3
PCFICH = 1 => CCE set index = N;
PCFICH = 2 => CCE set index = N + 1; And PCFICH = 3 => CCE set index = N + 2

Pattern 2-1
PCFICH = 1 => CCE set index = L;
PCFICH = 2 => CCE set index = M; And PCFICH = 3 => CCE set index = N

Pattern 2-2
PCFICH = 1 => CCE set index = L + 1;
PCFICH = 2 => CCE set index = M + 1; And PCFICH = 3 => CCE set index = N + 1

Pattern 2-3
PCFICH = 1 => CCE set index = L + 2;
PCFICH = 2 => CCE set index = M + 2; And PCFICH = 3 => CCE set index = N + 2

Pattern 3-1
PCFICH = 1 => CCE set index = L;
PCFICH = 2 => CCE set index = M; And PCFICH = 3 => CCE set index = N

Pattern 3-2
PCFICH = 1 => CCE set index = P;
PCFICH = 2 => CCE set index = Q, PCFICH = 3 => CCE set index = R

Pattern 3-3
PCFICH = 1 => CCE set index = S;
PCFICH = 2 => CCE set index = T; And PCFICH = 3 => CCE set index = U

C. How to use RS for antennas 4 ~ 7 for each channel

C-1) When it is not necessary to decode PCFICH information

The LTE-A system can apply TxD, MIMO precoding, SM, and beamforming using the RS of all 8 antenna ports to the downlink control channel (eg, PHICH, PCFICH, PDCCH of LTE Rel-8) . For this, channel estimation and CQI are measured using RS of LTE Rel-8 for antennas 0 to 3, and channel estimation and CQI are performed using newly designed RS based on CCE on LTE-A for antennas 4 to 7. [ By measuring CQI, it is possible to use all RSs of 8 antenna ports. In addition, the TxD, MIMO precoding, and SM methods using RSs of eight antenna ports are performed on a data channel (e.g., LTE Rel-8's PDSCH). In this case, in order to satisfy the channel estimation accuracy or time-varying property which is insufficient in the time axis, the MIMO scheme can be applied by additionally using a multiplexed / embedded dedicated RS in the data have. Similar to the above-mentioned control channel, the channel estimation and CQI are measured using the RS used in LTE Rel-8 for antennas 0 to 3, and the additional RS (i.e., MIMO precoding, SM or beamforming method using RSs of eight antenna ports by measuring channel estimation and CQI using RSs allocated to a control channel or RS allocated to a data channel, .

In the method of applying the MIMO technique using a plurality of antennas to the control channel and the data channel, it is proposed to use the same MIMO method for the control channel and the data channel for each subframe. For example, 8TxD can be used for control and data channels. Or a precoding technique may be used for the control channel and the data channel. Also, a method of applying different MIMO techniques to the control channel and the data channel in each subframe in each subframe is also presented. For example, one of 8xD for a control channel (e.g., PHICH, PCFICH, PDCCH) and TxD, SM, precoding and beamforming for a data channel (e.g., PDSCH) Also, a method of applying different MIMO techniques depending on the type of control channel can be considered. In addition, although the LTE Rel-8/9 terminal utilizes the MIMO scheme in the 4Tx for the control channel / data channel, Rel-10 or later terminals in the same subframe use the MIMO scheme using 8Tx, Can be considered.

C-2) When PCFICH information needs to be decoded

If the RS position is not fixed independently for the PCFICH information or control channel (eg, PHICH, PCFICH, PDCCH, etc.) on the time axis and frequency axis, LTE-A can use two or four antennas 2 or 4Tx transmit antenna diversity of existing LTE rel-8 by using two or four physical antennas using RS of the port, or by bundling eight physical antennas into four or two units, respectively, , MIMO precoding, SM or beamforming method to the downlink control channel (e.g., PHICH, PCFICH, PDCCH of LTE Rel-8). The remaining PDSCHs propose a downlink transmission method using TxD or precoding or a series of beamforming using all or part of the RSs of the eight antenna ports. The receiving end of the LTE-A system transmits control channels (e.g., PHICH, PCFICH , PDCCH) is transmitted using eight transmit antennas, it is not possible to know the information of the control channel (e.g., PHICH, PCFICH, PDCCH) using the RS corresponding to each antenna port used in the LTE Rel- Decoding is performed first. After receiving the control channel information, position information on the RS for supporting the 4 ~ 7 physical antennas or antenna ports allocated on the time and frequency axes is obtained. (TxD, MIMO precoding, SM, or beamforming) using the RSs of the eight antenna ports by acquiring the location information of the RS and using the channel estimation and channel measurement information through the RS. -8 &lt; / RTI &gt; PDSCH).

In addition, PCFICH uses two or four physical antennas using RSs of two or four antenna ports used in LTE Rel-8, or bundles eight physical antennas in units of four or two to form an antenna virtualization method And transmits the data in the TxD scheme using the 2Tx or 4Tx transmit antenna diversity scheme of the existing LTE Rel-8, and the remaining PDCCH and PDSCH are downlinked using TxD using 8 transmit antennas. At this time, each terminal acquires information on the PCFICH by channel estimation through the RS corresponding to each antenna port used in the LTE Rel-8. After acquiring information on the PCFICH, position information on the RS for supporting up to 4 ~ 7 physical antennas or antenna ports allocated on the time axis and the frequency axis is obtained. Thereafter, through the RS for supporting the antennas 4 to 7, the channels for the antennas 4 to 7 are estimated, and the RSs of the remaining 8 antenna ports (designated by LTE Rel-8 Using the proposed CCE-based RS for antennas 4 to 7 added in the common RS + LTE-A of the four antenna ports, using the received signals of PDCCH and PDSCH using TxD, (E.g., PDCCH) and a data channel (e.g., PDSCH) by applying it to a received signal of a PDSCH transmitted using a coding or a series of beamforming.

In the method of applying the MIMO technique using a plurality of antennas to the control channel and the data channel, it is proposed to use the same MIMO method for each control channel and data channel for each subframe. For example, a TxD that uses four antennas for the control and data channels can be used. Or the same precoding technique may be used for the control channel and the data channel. In addition, we propose applying different MIMO schemes for control channel and data channel in subframe for each subframe. That is, one of TxD using four antennas for the control channel (e.g., PHICH, PCFICH, and PDCCH), TxD using eight transmit antennas for the data channel, precoding, SM, and beamforming can be applied. A method of applying different MIMO techniques depending on the type of control channel can also be considered.

Concrete example  4: Using traffic resources RS  send

In the case of traffic resources, a method of allocating a resource to be used as an RS in a base station can be implemented very easily. However, a traffic resource used by an existing legacy terminal (e.g., LTE Rel-8 terminal) can not change its structure. Alternatively, in the case of a traffic channel used by a new terminal (e.g., LTE-A terminal), its structure can be predetermined and transmitted. For example, if the structure of the PDSCH is defined as it is, a predefined set of localized / distributed RBs (both virtual RBs or physical RBs) can be predetermined and the RS structure can be newly Can be defined. However, current ubiquitous / distributed RBs do not have a uniformly distributed structure across the entire band because the structure is based on legacy RSs that already exist. Therefore, it is possible to pre-allocate existing ubiquitous / distributed RBs to define RBs for LTE-A and to define new allocation structures in the corresponding RBs. Define RS subcarriers (which may be defined over one or more OFDM symbols) and distribute the rest in a distributed or ubiquitous form Can be redefined as.

Considering the multi-carrier in the downlink, the specific component carrier of the downlink may be allocated only as an LTE-A only carrier. Therefore, the RSs for the antenna ports 4 to 7 are additionally allocated by using N (&gt; = 1) OFDM symbols at fixed positions allocated for data transmission for each subframe or each subframe period for each component carrier . When this method is used, it is possible to perform CDM and FDM as the multiplexing method for antenna ports # 4 to # 7. In the CDM method, for example, CAZAC sequences are assigned and different cyclic shifts of CAZAC sequences are assigned as RS sequences, so that orthogonal characteristics can be obtained for each antenna. In the FDM method, RPF composed of a multiple of 4 can be applied to allocate RSs for antennas 4 to 7. For example, if (freq._index mod 4) = 0, RS for antenna # 4, (freq._index mod 4) = 1, then RS for antenna # 5, 1, it is possible to allocate RSs for antenna # 7 when RS for # 6 antenna ((freq.index mod 4) = 1). A similar configuration is used to assign RSs for different antennas to different component carriers for the same time.

In addition, the method of multiplexing RSs among component carriers can be a method of CDM, TDM and FDM, and a hybrid method of FDM and CDM. The FDM method can be a form that depends on the number of total component carriers using RPF. For example, when there are two DL component carriers usable in the downlink, it is possible to perform multiplexing among the component carriers by allocating the RS to the entire band or the band to be scheduled at intervals of two spaces. As one embodiment, considering the RS multiplexing method between the component carriers and the antennas, it is possible to perform multiplexing with the CDM between the component carriers and with the FDM between the antennas. In addition, the multiplexing can be performed between the antennas by the CDM and the FDM between the component carriers.

Hereinafter, the case of allocating RSs by additionally using OFDM symbols in the PDSCH will be specifically described with reference to FIGS. 29 to 45. FIG. In case of LTE Rel-8, the subframe is composed of a control region and a data region, and the PDSCH is set in the remaining region excluding the reference signals for the antenna ports 0 to 3 in the data region. When the LTE Rel-8 operates in a closed loop rank 1 transmission mode, the PDSCH is set in the remaining area excluding the reference signal for the antenna port 5 in the data area. The detailed structure of the subframe can be referenced to FIGS. A box indicated by a bold line in the drawing represents a resource block, and each cell represents a resource element (RE) defined by one OFDM symbol and one subcarrier. The resource block is illustrated as being composed of 7 OFDM symbols 占 12 subcarriers. RE is a reference signal allocated by the sub-frame may be indicated by a combination of an OFDM symbol index, and a subcarrier index (l, k) _S. Here, l increases from left to right as an OFDM symbol index. k is a subcarrier index and increases from the lower side to the upper side. The subscript S is a slot index of 1 or 2. In the resource block, l is 0 to 6 or 0 to 5 and k is 0 to 12.

Tables 7 and 8 show patterns in which the reference signals for the existing antenna ports 0 to 3 are allocated in the subframe. Tables 7 and 8 show the case where the normal CP is used and the case where the extended CP is used, respectively.

Slot 1 Slot 2 l = 0 l = 1 l = 4 l = 0 l = 1 l = 4 k = 9 R1 R3 R0 R1 R2 R0 k = 6 R0 R2 R1 R0 R3 R1 k = 3 R1 R3 R0 R1 R2 R0 k = 0 R0 R2 R1 R0 R3 R1

Slot 1 Slot 2 l = 0 l = 1 l = 3 l = 0 l = 1 l = 3 k = 9 R1 R3 R0 R1 R2 R0 k = 6 R0 R2 R1 R0 R3 R1 k = 3 R1 R3 R0 R1 R2 R0 k = 0 R0 R2 R1 R0 R3 R1

Tables 9 and 10 show a pattern in which a reference signal for an existing antenna port 5 is allocated in a subframe. Tables 9 and 10 show the case where the normal CP is used and the case where the extended CP is used, respectively.

Slot 1 Slot 2 l = 3 l = 6 l = 2 l = 5 k = 10 - R5 - R5 k = 8 R5 - R5 - k = 6 - R5 - R5 k = 4 R5 - R5 - k = 2 - R5 - R5 k = 0 R5 - R5 -

Slot 1 Slot 2 l = 4 l = 1 l = 4 k = 11 R5 k = 9 R5 R5 k = 8 R5 k = 6 R5 R5 k = 5 R5 k = 3 R5 R5 k = 2 R5 k = 0 R5 R5

29 to 32 illustrate the case of allocating RSs for antenna ports 6 to 9 (R6 to R9) by additionally using four OFDM symbols. In the drawing, the left part indicates a case where a normal CP is used and the right part indicates a case where an extended CP is used. The figure assumes that the control region is composed of the first one or two OFDM symbols of a subframe.

The patterns A-1 to A-4 are designed to maintain a spacing of four spaces on the frequency axis for the extended antenna port. The A-1 and A-3 patterns show the case where RSs for each antenna port are allocated to each of the four additional OFDM symbols. A-2 and A-4 represent the case where RSs for each antenna port are allocated over two OFDM symbols to reflect channel changes on the time axis.

The patterns A-5 to A-8 show the case where the RS for the extended antenna port is designed to have the same overhead as the RS of the LTE Rel-8. The RS for each extended antenna port is designed to maintain a space of three spaces along the frequency axis. The A-5 pattern represents a case where RSs for each antenna port are allocated to each of four additional OFDM symbols. A-6 and A-7 illustrate the case where RSs for each antenna port are allocated over four OFDM symbols to reflect channel changes on the time axis. The A-8 pattern shows a case where RSs for each antenna port are allocated over two OFDM symbols to reflect channel changes on the time axis and the frequency axis.

The antenna ports 6 to 9 (R6 to R9) extended in the patterns A-1 to A-8 can be mutually changed in position. In addition, the RS for the extended antenna port can be equally applied to the position shift on the frequency axis used for reducing the interference of the inter-cell RSs, v_shift (v_shift = cell_id mod 3) applied to the existing antenna port 5 have.

The RS positions of R6 to R9 according to the patterns A-1 to A-8 are as follows. For convenience, only the position of the RS with respect to the normal CP is shown. In the case of the extended CP, the RS has the same RS overhead and pattern as the case of the normal CP, and the position of the OFDM symbol to which the RS is allocated differs as the number of OFDM symbols in the subframe varies.

A-1 pattern (Fig. 29)

R6 (1, k) _S = {(2,0) ₁ , (2,4) ₁ , (2,8) ₁ }; _{R7 (l, k) S =} {(5,2) 1, (5,6) 1, (5,10) 1}
R8 (1, k) _S = {(3,0) ₂ , (3,4) ₂ , (3,8) ₂ }; R9 (l, k) _S = {(6,2) ₂ , (6,6) ₂ , (6,10) ₂ }

A-2 pattern (Figure 29)

R6 (1, k) _S = {(2,0) ₁ , (2,8) ₁ , (3,4) ₂ }; R7 (l, k) _S = {(5,2) ₁ , (5,10) ₁ , (6,6) ₂ }
R8 (1, k) _S = {(2,4) ₁ , (3,0) ₂ , (3,8) ₂ }; R9 (l, k) _S = {(5,6) ₁ , (6,2) ₂ , (6,10) ₂ }

A-3 pattern (Fig. 30)

R6 (1, k) _S = {(2,0) ₁ , (2,4) ₁ , (2,8) ₁ }; _{R7 (l, k) S =} {(5,0) 1, (5,4) 1, (5,8) 1}
R8 (1, k) _S = {(3,0) ₂ , (3,4) ₂ , (3,8) ₂ }; R9 (l, k) _S = {(6,0) ₂ , (6,4) ₂ , (6,8) ₂ }

A-4 pattern (Figure 30)

R6 (1, k) _S = {(2,0) ₁ , (2,8) ₁ , (3,4) ₂ }; R7 (l, k) _S = {(5,0) ₁ , (5,8) ₁ , (6,4) ₂ }
R8 (1, k) _S = {(2,4) ₁ , (3,0) ₂ , (3,8) ₂ }; R9 (l, k) _S = {(5,4) ₁ , (6,0) ₂ , (6,8) ₂ }

A-5 pattern (Fig. 31)

R6 (1, k) _S = {(2,0) ₁ , (2,3) ₁ , (2,6) ₁ , (2,9) ₁ }; _{R7 (l, k) S =} {(5,0) 1, (5,3) 1, (5,6) 1, (5,9) 1}
R8 (1, k) _S = {(3,0) ₂ , (3,3) ₂ , (3,6) ₂ , (3,9) ₂ }; _{R9 (l, k) S =} {(6,0) 2, (6,3) 2, (6,6) 2, (6,9) 2}

A-6 pattern (Fig. 31)

R6 (1, k) _S = {(2,9) ₁ , (5,6) ₁ , (3,3) ₂ , (6,0) ₂ }; _{R7 (l, k) S =} {(2,6) 1, (5,3) 1, (3,0) 2, (6,9) 2}
R8 (1, k) _S = {(2,3) ₁ , (5,0) ₁ , (3,9) ₂ , (6,6) ₂ }; _{R9 (l, k) S =} {(2,0) 1, (5,9) 1, (3,6) 2, (6,3) 2}

A-7 pattern (Fig. 32)

R6 (1, k) _S = {(2,0) ₁ , (5,3) ₁ , (3,6) ₂ , (6,9) ₂ }; _{R7 (l, k) S =} {(2,9) 1, (5,0) 1, (3,3) 2, (6,6) 2}
R8 (1, k) _S = {(2,6) ₁ , (5,9) ₁ , (3,0) ₂ , (6,3) ₂ }; _{R9 (l, k) S =} {(2,3) 1, (5,6) 1, (3,9) 2, (6,0) 2}

A-8 pattern (Fig. 32)

R6 (1, k) _S = {(2,3) ₁ , (2,9) ₁ , (3,0) ₂ , (3,6) ₂ }; _{R7 (l, k) S =} {(5,3) 1, (5,9) 1, (6,0) 2, (6,6) 2}
R8 (1, k) _S = {(2,0) ₁ , (2,6) ₁ , (3,3) ₂ , (3,9) ₂ }; _{R9 (l, k) S =} {(5,0) 1, (5,6) 1, (6,3) 2, (6,9) 2}

33 and 34 illustrate the case of allocating RSs for antenna ports 6 to 9 (R6 to R9) by additionally using three OFDM symbols. In the figure, the left part indicates a case in which a normal CP is used and the right part indicates an extended CP.

The patterns B-1 to B-4 are designed to maintain a spacing of 3 to 3 in the frequency axis for the extended antenna port. The patterns B-1 to B-4 represent the case where RSs for each antenna port are allocated over three OFDM symbols to reflect channel changes on the time axis. In particular, the patterns B-1 and B-2 represent the case where the control region is composed of the first three OFDM symbols of a subframe. In this case, since the third OFDM symbol in the subframe is used as the resource of the control region, the RS for the extended antenna port can be allocated from the first 6th OFDM symbol of the subframe. When the control region is composed of the first two or less OFDM symbols in the subframe, all the patterns B-1 to B-4 can be applied.

The antenna ports 6 to 9 (R6 to R9) extended from the pattern B-1 to the pattern B-4 may be displaced from each other. In addition, the RS for the extended antenna port can be equally applied to the position shift on the frequency axis used for reducing the interference of the inter-cell RSs, v_shift (v_shift = cell_id mod 3) applied to the existing antenna port 5 have.

The RS positions of R6 to R9 according to the patterns B-1 to B-4 are as follows. For convenience, only the position of the RS with respect to the normal CP is shown. In the case of the extended CP, the RS has the same RS overhead and pattern as the case of the normal CP, and the position of the OFDM symbol to which the RS is allocated differs as the number of OFDM symbols in the subframe varies.

B-1 pattern (Fig. 32)

R6 (1, k) _S = {(5,9) ₁ , (3,6) ₂ , (6,3) ₂ }; R7 (l, k) _S = {(5,6) ₁ , (3,3) ₂ , (6,0) ₂ }
R8 (1, k) _S = {(5,3) ₁ , (3,0) ₂ , (6,9) ₂ }; R9 (1, k) _S = {(5,0) ₁ , (3,9) ₂ , (6,6) ₂ }

B-2 pattern (Fig. 32)

R6 (1, k) _S = {(5,3) ₁ , (3,6) ₂ , (6,9) ₂ }; R7 (l, k) _S = {(5,0) ₁ , (3,3) ₂ , (6,6) ₂ }
R8 (1, k) _S = {(5,9) ₁ , (3,0) ₂ , (6,3) ₂ }; R9 (l, k) _S = {(5,6) ₁ , (3,9) ₂ , (6,0) ₂ }

The B-3 pattern (Figure 33)

R6 (1, k) _S = {(2,9) ₁ , (5,6) ₁ , (3,3) ₂ }; R7 (l, k) _S = {(2,6) ₁ , (5,3) ₁ , (3,0) ₂ }
R8 (1, k) _S = {(2,3) ₁ , (5,0) ₁ , (3,9) ₂ }; R9 (1, k) _S = {(2,0) ₁ , (5,9) ₁ , (3,6) ₂ }

The B-4 pattern (Figure 33)

R6 (1, k) _S = {(2,3) ₁ , (5,6) ₁ , (3,9) ₂ }; R7 (l, k) _S = {(2,0) ₁ , (5,3) ₁ , (3,6) ₂ }
R8 (1, k) _S = {(2,9) ₁ , (5,0) ₁ , (3,3) ₂ }; R9 (1, k) _S = {(2,6) ₁ , (5,9) ₁ , (3,3) ₂ }

35 to 42 illustrate the case of allocating RSs for antenna ports 6 to 9 (R6 to R9) by additionally using two OFDM symbols. In the figure, the left part indicates a case in which a normal CP is used and the right part indicates an extended CP.

The C-1 through C-16 patterns are designed to maintain a spacing of four spaces on the frequency axis for the extended antenna port. The C-1, C-3, C-5, C-7, and C-9 patterns indicate the case where RSs for each antenna port are allocated to each of the two additional OFDM symbols. The patterns C-2, C-4, C-6, C-8, and C-10 show the case where RSs for each antenna port are allocated over two OFDM symbols to reflect channel changes on the time axis. The C-11 to C-16 patterns show the case where the RS for the extended antenna port is designed to have the same overhead as the RS of the LTE Rel-8. Particularly, the C-1 to C-6 patterns show the case where the control region is composed of the first three OFDM symbols of the subframe. In this case, since the third OFDM symbol in the subframe is used as the resource of the control region, the RS for the extended antenna port can be allocated from the first 6th OFDM symbol of the subframe. When the control region is composed of the first two or less OFDM symbols in the subframe, all the C-1 to C-16 patterns can be applied.

The antenna ports 6 to 9 (R6 to R9) extended from the C-1 to C-16 patterns can be mutually shifted. In addition, the RS for the extended antenna port can be equally applied to the position shift on the frequency axis used for reducing the interference of the inter-cell RSs, v_shift (v_shift = cell_id mod 3) applied to the existing antenna port 5 have.

The RS positions of R6 to R9 according to the patterns C-1 to C-16 are as follows. For convenience, only the position of the RS with respect to the normal CP is shown. In the case of the extended CP, the RS has the same RS overhead and pattern as the case of the normal CP, and the position of the OFDM symbol to which the RS is allocated differs as the number of OFDM symbols in the subframe varies.

The C-1 pattern (Figure 35)

R6 (1, k) _S = {(5,0) ₁ , (5,4) ₁ , (5,8) ₁ }; _{R7 (l, k) S =} {(5,1) 1, (5,5) 1, (5,9) 1}
R8 (1, k) _S = {(3,0) ₂ , (3,4) ₂ , (3,8) ₂ }; R9 (1, k) _S = {(3,1) ₂ , (3,5) ₂ , (3,9) ₂ }

The C-2 pattern (Figure 35)

R6 (1, k) _S = {(5,0) ₁ , (5,8) ₁ , (3,4) ₂ }; _{R7 (l, k) S =} {(5,1) 1, (5,9) 1, (3,5) 2}
R8 (1, k) _S = {(5,4) ₁ , (3,0) ₂ , (3,8) ₂ }; R9 (l, k) _S = {(5,5) ₁ , (3,1) ₂ , (3,9) ₂ }

The C-3 pattern (Figure 36)

R6 (1, k) _S = {(5,0) ₁ , (5,4) ₁ , (5,8) ₁ }; _{R7 (l, k) S =} {(5,1) 1, (5,5) 1, (5,9) 1}
R8 (1, k) _S = {(6,0) ₂ , (6,4) ₂ , (6,8) ₂ }; R9 (l, k) _S = {(6,1) ₂ , (6,5) ₂ , (6,9) ₂ }

The C-4 pattern (Figure 36)

R6 (1, k) _S = {(5,0) ₁ , (5,8) ₁ , (6,4) ₂ }; R7 (l, k) _S = {(5,1) ₁ , (5,9) ₁ , (6,5) ₂ }
R8 (1, k) _S = {(5,4) ₁ , (6,0) ₂ , (6,8) ₂ }; R9 (l, k) _S = {(5,5) ₁ , (6,1) ₂ , (6,9) ₂ }

The C-5 pattern (Figure 37)

R6 (1, k) _S = {(3,0) ₂ , (3,4) ₂ , (3,8) ₂ }; R7 (l, k) _S = {(3,1) ₂ , (3,5) ₂ , (3,9) ₂ }
R8 (1, k) _S = {(6,0) ₂ , (6,4) ₂ , (6,8) ₂ }; R9 (l, k) _S = {(6,1) ₂ , (6,5) ₂ , (6,9) ₂ }

The C-6 pattern (Figure 37)

R6 (1, k) _S = {(3,0) ₂ , (3,8) ₂ , (6,4) ₂ }; R7 (l, k) _S = {(3,1) ₂ , (3,9) ₂ , (6,5) ₂ }
R8 (1, k) _S = {(3,4) ₂ , (6,0) ₂ , (6,8) ₂ }; R9 (l, k) _S = {(3,5) ₂ , (6,1) ₂ , (6,9) ₂ }

The C-7 pattern (Figure 38)

R6 (1, k) _S = {(2,0) ₁ , (2,4) ₁ , (2,8) ₁ }; _{R7 (l, k) S =} {(2,1) 1, (2,5) 1, (2,9) 1}
R8 (1, k) _S = {(3,0) ₂ , (3,4) ₂ , (3,8) ₂ }; R9 (1, k) _S = {(3,1) ₂ , (3,5) ₂ , (3,9) ₂ }

The C-8 pattern (Figure 38)

R6 (1, k) _S = {(2,0) ₁ , (2,8) ₁ , (3,4) ₂ }; _{R7 (l, k) S =} {(2,1) 1, (2,9) 1, (3,5) 2}
R8 (1, k) _S = {(2,4) ₁ , (3,0) ₂ , (3,8) ₂ }; R9 (l, k) _S = {(2,5) ₁ , (3,1) ₂ , (3,9) ₂ }

The C-9 pattern (Figure 39)

R6 (1, k) _S = {(2,0) ₁ , (2,4) ₁ , (2,8) ₁ }; _{R7 (l, k) S =} {(2,1) 1, (2,5) 1, (2,9) 1}
R8 (1, k) _S = {(6,0) ₂ , (6,4) ₂ , (6,8) ₂ }; R9 (l, k) _S = {(6,1) ₂ , (6,5) ₂ , (6,9) ₂ }

The C-10 pattern (Figure 39)

R6 (1, k) _S = {(2,0) ₁ , ( ₂ , 8) ₁ , ( ₆ , 4) ₂ }; R7 (l, k) _S = {(2,1) ₁ , (2,9) ₁ , (6,5) ₂ }
R8 (1, k) _S = {(2,4) ₁ , (6,0) ₂ , (6,8) ₂ }; R9 (l, k) _S = {(2,5) ₁ , (6,1) ₂ , (6,9) ₂ }

The C-11 pattern (Figure 40)

R6 (1, k) _S = {(2,2) ₁ , (2,8) ₁ , (3,0) ₂ , (3,6) ₂ }; _{R7 (l, k) S =} {(2,3) 1, (2,9) 1, (3,1) 2, (3,7) 2}
R8 (1, k) _S = {(2,0) ₁ , (2,6) ₁ , (3,2) ₂ , (3,8) ₂ }; _{R9 (l, k) S =} {(2,1) 1, (2,7) 1, (3,3) 2, (3,9) 2}

The C-12 pattern (Figure 40)

R6 (1, k) _S = {(2,3) ₁ , (2,9) ₁ , (3,0) ₂ , (3,6) ₂ }; _{R7 (l, k) S =} {(2,0) 1, (2,6) 1, (3,3) 2, (3,9) 2}
R8 (1, k) _S = {(2,4) ₁ , (2,10) ₁ , (3,1) ₂ , (3,7) ₂ }; _{R9 (l, k) S =} {(2,1) 1, (2,7) 1, (3,4) 2, (3,10) 2}

The C-13 pattern (Figure 41)

R6 (1, k) _S = {(2,3) ₁ , (2,9) ₁ , (3,1) ₂ , (3,7) ₂ }; _{R7 (l, k) S =} {(2,0) 1, (2,6) 1, (3,4) 2, (3,10) 2}
R8 (1, k) _S = {(2,4) ₁ , (2,10) ₁ , (3,2) ₂ , (3,8) ₂ }; _{R9 (l, k) S =} {(2,1) 1, (2,7) 1, (3,5) 2, (3,11) 2}

The C-14 pattern (Figure 41)

R6 (1, k) _S = {(5,2) ₁ , (5,8) ₁ , (6,0) ₂ , (6,6) ₂ }; _{R7 (l, k) S =} {(5,3) 1, (5,9) 1, (6,1) 2, (6,7) 2}
R8 (1, k) _S = {(5,0) ₁ , (5,6) ₁ , (6,2) ₂ , (6,8) ₂ }; _{R9 (l, k) S =} {(5,1) 1, (5,7) 1, (6,3) 2, (6,9) 2}

The C-15 pattern (Figure 42)

R6 (1, k) _S = {(5,3) ₁ , (5,9) ₁ , (6,0) ₂ , (6,6) ₂ }; _{R7 (l, k) S =} {(5,0) 1, (5,6) 1, (6,3) 2, (6,9) 2}
R8 (1, k) _S = {(5,4) ₁ , (5,10) ₁ , (6,1) ₂ , (6,7) ₂ }; _{R9 (l, k) S =} {(5,1) 1, (5,7) 1, (6,4) 2, (6,10) 2}

The C-16 pattern (Figure 42)

R6 (1, k) _S = {(5,3) ₁ , (5,9) ₁ , (6,1) ₂ , (6,7) ₂ }; _{R7 (l, k) S =} {(5,0) 1, (5,6) 1, (6,4) 2, (6,10) 2}
R8 (1, k) _S = {(5,4) ₁ , (5,10) ₁ , (6,2) ₂ , (6,8) ₂ }; _{R9 (l, k) S =} {(5,1) 1, (5,7) 1, (6,5) 2, (6,11) 2}

43 and 44 illustrate the case of allocating RSs for antenna ports 6 to 9 (R6 to R9) by additionally using one OFDM symbol. In the figure, the left part indicates a case in which a normal CP is used and the right part indicates an extended CP.

The D-1 through D-4 patterns are designed to maintain a spacing of four spaces on the frequency axis for the extended antenna port. In particular, the patterns D-1 to D-3 show the case where the control region is composed of the first three OFDM symbols of the subframe. In this case, since the third OFDM symbol in the subframe is used as the resource of the control region, the RS for the extended antenna port can be allocated from the first 6th OFDM symbol of the subframe. If the control region is composed of the first two or less OFDM symbols in the subframe, all of the patterns D-1 to D-4 can be applied.

The extended antenna ports 6 to 9 (R6 to R9) in the patterns D-1 to D-4 may be mutually shifted. In addition, the RS for the extended antenna port can be equally applied to the position shift on the frequency axis used for reducing the interference of the inter-cell RSs, v_shift (v_shift = cell_id mod 3) applied to the existing antenna port 5 have. In particular, the D-1 pattern indicates a case where the control region is composed of the first three OFDM symbols of a subframe. In this case, since the third OFDM symbol in the subframe is used as the resource of the control region, the RS for the extended antenna port can be allocated from the first 6th OFDM symbol of the subframe. If the control region is composed of the first two or less OFDM symbols in the subframe, all of the patterns D-1 to D-4 can be applied.

The RS positions of R6 to R9 according to the patterns D-1 to D-4 are as follows. For convenience, only the position of the RS with respect to the normal CP is shown. In the case of the extended CP, the RS has the same RS overhead and pattern as the case of the normal CP, and the position of the OFDM symbol to which the RS is allocated differs as the number of OFDM symbols in the subframe varies.

The D-1 pattern (Figure 43)

R6 (l, k) _S = {(5,3) ₁ , (5,7) ₁ , (5,11) ₁ }; _{R7 (l, k) S =} {(5,2) 1, (5,6) 1, (5,10) 1}
R8 (1, k) _S = {(5, ₁ ) ₁ , (5, 5) ₁ , (5, 9) ₁ }; _{R9 (l, k) S =} {(5,0) 1, (5,4) 1, (5,8) 1}

The D-2 pattern (Figure 43)

R6 (1, k) _S = {(3,3) ₂ , (3,7) ₂ , (3, ₁₁ ) ₂ }; R7 (l, k) _S = {(3,2) ₂ , (3,6) ₂ , (3,10) ₂ }
R8 (1, k) _S = {(3,1) ₂ , (3,5) ₂ , (3,9) ₂ }; R9 (l, k) _S = {(3,0) ₂ , (3,4) ₂ , (3,8) ₂ }

The D-3 pattern (Figure 44)

R6 (l, k) _S = {(6,3) ₂ , (6,7) ₂ , (6,11) ₂ }; R7 (l, k) _S = {(6,2) ₂ , (6,6) ₂ , (6,10) ₂ }
R8 (1, k) _S = {(6,1) ₂ , (6,5) ₂ , (6,9) ₂ }; R9 (l, k) _S = {(6,0) ₂ , (6,4) ₂ , (6,8) ₂ }

The D-4 pattern (Figure 44)

R6 (1, k) _S = {(2,3) ₁ , (2,7) ₁ , (2,11) ₁ }; _{R7 (l, k) S =} {(2,2) 1, (2,6) 1, (2,10) 1}
R8 (1, k) _S = {(2,1) ₁ , (2,5) ₁ , (2,9) ₁ }; _{R9 (l, k) S =} {(2,0) 1, (2,4) 1, (2,8) 1}

FIG. 45 illustrates a case where an RS for an extended antenna port 6 to 9 (R6 to R9) is allocated using an OFDM symbol to which an existing RS is allocated.

The E-1 and E-2 patterns are designed to maintain a 4-space interval on the frequency axis for the extended antenna port, and RSs for each antenna port are allocated over three OFDM symbols to reflect channel changes on the time axis. .

The extended antenna ports 6 to 9 (R6 to R9) in the E-1 and E-2 patterns can be shifted from each other. In addition, the RS for the extended antenna port can be equally applied to the position shift on the frequency axis used for reducing the interference of the inter-cell RSs, v_shift (v_shift = cell_id mod 3) applied to the existing antenna port 5 have.

The RS positions of R6 to R9 according to the patterns E-1 and E-2 are as follows. In the case of the extended CP, the RS has the same RS overhead and pattern as the case of the normal CP, and the position of the OFDM symbol to which the RS is allocated differs as the number of OFDM symbols in the subframe varies.

The E-1 pattern (Figure 45)

R6 (1, k) _S = {(3,9) ₁ , (6,5) ₁ , (2,1) ₂ }; R7 (l, k) _S = {(6,9) ₁ , (2,5) ₂ , (5,1) ₂ }
R8 (1, k) _S = {(3, ₁ ) ₁ , ( ₂ , 9) ₂ , (5, 5) ₂ }; R9 (1, k) _S = {(3,5) ₁ , (6,1) ₁ , (5,9) ₂ }

The E-2 pattern (Figure 45)

R6 (1, k) _S = {(3, ₁ ) ₁ , ( ₆ , 5) ₁ , (2, 9) ₂ }; R7 (l, k) _S = {(6,1) ₁ , (2,5) ₂ , (5,9) ₂ }
R8 (1, k) _S = {(3,9) ₁ , (2,1) ₂ , (5,5) ₂ }; R9 (l, k) _S = {(3,5) ₁ , (6,9) ₁ , (5,1) ₂ }

The A to E patterns according to the embodiment of the present invention illustrate the case where RSs for the extended four antennas are multiplexed in the form of FDM and TDM. However, the RS pattern illustrated above is an example, and it is also possible to multiplex a subset of resources for allocating RSs for antenna ports 6-9 in the form of CDM. For example, referring to the A-1 pattern, it can be seen that a total of six REs are used for the RSs at antenna port 6 and antenna port 8 (three at each). In this case, six RSs for each of the antenna ports 6 and 8 are redundantly allocated to the six REs, and RSs for the extended antennas are multiplexed in a CDM manner by allocating different codes or sequences for each antenna port . In addition, the RS for the extended antenna can be multiplexed in the form of CDM using all of the REs to which the RS for the extended antenna is allocated. For example, referring to the A-1 pattern, it can be seen that a total of twelve REs are used for the RSs of the antenna ports 6 through 9 (three each). In this case, twelve RSs for each antenna port may be redundantly allocated to the twelve REs, and RSs for the extended four antennas may be multiplexed in CDM by allocating different codes or sequences for each antenna port. The multiplexing of the RS for the extended antenna by the CDM method can be applied to all of the A to E patterns.

Embodiment 4 can be used to independently transmit RSs for antennas 4 to 7 and can additionally be used for the transmission scheme of the RS mentioned in Embodiment 1. [

As an example, it may be considered to use the method of embodiment 1 and the method of embodiment 4 together between the antennas to transmit the RS for antennas 4 to 7. For example, in case of an RS for antennas 4 and 5, a reserved CCE is assigned to a PDCCH, and in case of an RS for antennas 6 and 7, an additional OFDM symbol in a downlink data channel or a fixed RB A method of transmitting an RS by using the RS may be considered. In a similar manner, a reserved CCE of the PDCCH is allocated to the RS of a specific antenna and an OFDM symbol of the downlink data channel of the LTE Rel-8 according to the fourth specific example is allocated to a certain RB in the frequency domain There is a way to do it.

As another example, the RS for antennas 4 to 7 is assigned to a region allocated to a PDCCH in a specific subframe for each subframe as shown in Example 1, and after a certain period of transmitting RS, an OFDM symbol Or a method that can be allocated in the form of FDM, TDM, or CDM between antennas in a subframe used only for a certain RB or LTE-A in the frequency domain.

Concrete example  5: Antenna port 5 RS  Pattern for antennas 4 to 7 RS  Reuse as a resource

If the RS pattern for classical beamforming is applied to antennas 4 to 7, it is assumed that antenna port 5 is not used for classical beamforming, and RS of antenna port 5 defined in LTE Rel- Pattern or antenna port 5 is reused for RS for antennas 4 to 7 of LTE-A as it is. TDM, FDM, and CDM methods can be multiplexed between antennas 4 and 7 with the same density. In addition, the method of the fifth embodiment can be considered as an additional method for the first embodiment as in the fifth embodiment as a method of applying the RS to the antennas 4 to 7, and further, the RS can be considered as the CSI- It is also suggested to use DM-RS for data demodulation.

As an example, consideration may be given to using the method of the first embodiment and the method of the fifth embodiment together between the antennas to transmit the RS for the antennas 4 to 7. For example. In case of RS for antennas 4 and 5, the reserved CCE is assigned to PDCCH, and in case of RS for antennas 6 and 7, RS pattern of antenna port 5 can be reused for antennas 6 and 7 as it is , Or an OFDM symbol used by antenna port 5 can be reused for antennas 6 and 7. In a similar manner, the reserved CCE of the PDCCH may be allocated to the RS of the specific antenna, and the method of the fifth embodiment may be used to the RS of the remaining antennas.

As another example, the RS for antennas 4 to 7 is assigned to a region allocated to a PDCCH in a specific subframe for each subframe as shown in Embodiment 1, and after a certain period of transmitting RS, It is possible to reuse the RS pattern of 5 to the RS for antennas 4 to 7, or to reuse the OFDM symbol used by the antenna port 5. In the subframe, RSs for antennas 4 to 7 may be allocated in the form of FDM, TDM, and CDM between antennas.

46 shows a pattern in which an RS for an antenna port 5 is allocated in a subframe. LTE Rel-8 defines antenna port 5 as being in closed loop rank 1 transmission mode. A box indicated by a bold line in the drawing represents a resource block, and each cell represents a resource element defined by one OFDM symbol and one subcarrier. Tables 9 and 10 can be referred to for the allocation pattern of RS for antenna port 5.

Hereinafter, the RS for the extended antenna port is reused and allocated to the existing antenna port 5 by referring to FIGS. 47 to 52. FIG. A new system (LTE-A) evolved from LTE Rel-8, by reusing the resource elements occupied by antenna port 5 defined in LTE Rel-8, has a backward compatibility can be maintained.

The patterns P-1 to P-8 are designed so that the RS for the extended antenna port maintains a space of four spaces on the frequency axis. The patterns P-1 to P-4 illustrate the case of using a normal CP. Specifically, the P-1 pattern is a case where RSs for each antenna port extended to each OFDM symbol are allocated. The P-2 pattern indicates a case where RSs for each antenna port are allocated over two OFDM symbols to reflect the channel change on the time axis. P-3 and P-4 patterns are a mixture of P-1 pattern and P-2 pattern. On the other hand, the patterns P-5 to P-8 illustrate the case where the extended CP is used. The patterns P-5 to P-8 show the case where RSs for each antenna port are allocated over three OFDM symbols to reflect channel changes on the time axis.

The extended antenna ports 6 to 9 (R6 to R9) in the patterns P-1 to P-8 may be mutually shifted. In addition, the RS for the extended antenna port can be equally applied to the position shift on the frequency axis used for reducing the interference of the inter-cell RSs, v_shift (v_shift = cell_id mod 3) applied to the existing antenna port 5 have.

P-1 pattern (Fig. 47)

R6 (1, k) _S = {(3,0) ₁ , (3,4) ₁ , (3,8) ₁ }; R7 (l, k) _S = {(2,0) ₂ , (2,4) ₂ , (2,8) ₂ }
R8 (1, k) _S = {(6,2) ₁ , (6,6) ₁ , (6,10) ₁ }; R9 (l, k) _S = {(5,2) ₂ , (5,6) ₂ , (5,10) ₂ }

P-2 pattern (Figure 48)

R6 (1, k) _S = {(3,0) ₁ , (3,8) ₁ , (2,4) ₂ }; R7 (l, k) _S = {(3,4) ₁ , (2,0) ₂ , (2,8) ₂ }
R8 (1, k) _S = {(6,2) ₁ , (6,10) ₁ , (5,6) ₂ }; R9 (l, k) _S = {(6,6) ₁ , (5,2) ₂ , (5,10) ₂ }

P-3 pattern (Fig. 48)

R6 (1, k) _S = {(3,0) ₁ , (3,4) ₁ , (3,8) ₁ }; R7 (l, k) _S = {(2,0) ₂ , (2,4) ₂ , (2,8) ₂ }
R8 (1, k) _S = {(6,2) ₁ , (6,10) ₁ , (5,6) ₂ }; R9 (l, k) _S = {(6,6) ₁ , (5,2) ₂ , (5,10) ₂ }

P-4 pattern (FIG. 48)

R6 (1, k) _S = {(3,0) ₁ , (3,8) ₁ , (2,4) ₂ }; _{R7 (l, k) S =} {(6,2) 1, (6,6) 1, (6,10) 1}
R8 (1, k) _S = {(3,4) ₁ , (2,0) ₂ , (2,8) ₂ }; R9 (l, k) _S = {(5,2) ₂ , (5,6) ₂ , (5,10) ₂ }

P-5-1 pattern (Fig. 49)

R6 (1, k) _S = {(4,9) ₁ , (1,5) ₂ , (4,0) ₂ }; R7 (l, k) _S = {(4,6) ₁ , (1,2) ₂ , (4,9) ₂ }
R8 (1, k) _S = {(4,3) ₁ , (1,11) ₂ , (4,6) ₂ }; R9 (l, k) _S = {(4,0) ₁ , (1,8) ₂ , (4,3) ₂ }

P-5-2 pattern (Fig. 49)

R6 (1, k) _S = {(4,9) ₁ , (1,2) ₂ , (4,6) ₂ }; R7 (l, k) _S = {(4,6) ₁ , (1,11) ₂ , (4,3) ₂ }
R8 (1, k) _S = {(4,3) ₁ , (1,8) ₂ , (4,0) ₂ }; R9 (1, k) _S = {(4,0) ₁ , (1,5) ₂ , (4,9) ₂ }

P-5-3 pattern (Fig. 49)

R6 (1, k) _S = {(4,9) ₁ , (1,8) ₂ , (4,0) ₂ }; R7 (l, k) _S = {(4,6) ₁ , (1,5) ₂ , (4,9) ₂ }
R8 (1, k) _S = {(4,3) ₁ , (1,2) ₂ , (4,6) ₂ }; R9 (l, k) _S = {(4,0) ₁ , (1,11) ₂ , (4,3) ₂ }

P-6-1 pattern (Fig. 50)

R6 (1, k) _S = {(4,0) ₁ , (1,8) ₂ , (4,3) ₂ }; R7 (l, k) _S = {(4,9) ₁ , (1,5) ₂ , (4,0) ₂ }
R8 (1, k) _S = {(4,6) ₁ , (1,2) ₂ , (4,9) ₂ }; R9 (l, k) _S = {(4,3) ₁ , (1,11) ₂ , (4,6) ₂ }

P-6-2 pattern (Fig. 50)

R6 (1, k) _S = {(4,0) ₁ , (1,5) ₂ , (4,9) ₂ }; R7 (l, k) _S = {(4,9) ₁ , (1,2) ₂ , (4,6) ₂ }
R8 (1, k) _S = {(4,6) ₁ , (1,11) ₂ , (4,3) ₂ }; R9 (1, k) _S = {(4,3) ₁ , (1,8) ₂ , (4,0) ₂ }

P-6-3 pattern (Fig. 50)

R6 (1, k) _S = {(4,0) ₁ , (1,11) ₂ , (4,3) ₂ }; R7 (l, k) _S = {(4,9) ₁ , (1,8) ₂ , (4,0) ₂ }
R8 (1, k) _S = {(4,6) ₁ , (1,5) ₂ , (4,9) ₂ }; R9 (l, k) _S = {(4,3) ₁ , (1,2) ₂ , (4,6) ₂ }

P-7-1 pattern (Fig. 51)

R6 (1, k) _S = {(4,3) ₁ , (1,11) ₂ , (4,6) ₂ }; R7 (l, k) _S = {(4,0) ₁ , (1,8) ₂ , (4,3) ₂ }
R8 (1, k) _S = {(4,9) ₁ , (1,5) ₂ , (4,0) ₂ }; R9 (l, k) _S = {(4,6) ₁ , (1,2) ₂ , (4,9) ₂ }

P-7-2 pattern (Fig. 51)

R6 (1, k) _S = {(4,3) ₁ , (1,8) ₂ , (4,0) ₂ }; R7 (l, k) _S = {(4,0) ₁ , (1,5) ₂ , (4,9) ₂ }
R8 (1, k) _S = {(4,9) ₁ , (1,2) ₂ , (4,6) ₂ }; R9 (l, k) _S = {(4,6) ₁ , (1,11) ₂ , (4,3) ₂ }

P-7-3 pattern (Fig. 51)

R6 (1, k) _S = {(4,3) ₁ , (1,2) ₂ , (4,6) ₂ }; R7 (l, k) _S = {(4,0) ₁ , (1,11) ₂ , (4,3) ₂ }
R8 (1, k) _S = {(4,9) ₁ , (1,8) ₂ , (4,0) ₂ }; R9 (1, k) _S = {(4,6) ₁ , (1,5) ₂ , (4,9) ₂ }

P-8-1 pattern (Fig. 52)

R6 (1, k) _S = {(4,6) ₁ , (1,2) ₂ , (4,9) ₂ }; R7 (l, k) _S = {(4,3) ₁ , (1,11) ₂ , (4,6) ₂ }
R8 (l, k) _S = {(4,0) ₁ , (1,8) ₂ , (4,3) ₂ }; R9 (1, k) _S = {(4,9) ₁ , (1,5) ₂ , (4,0) ₂ }

P-8-2 pattern (Fig. 52)

R6 (1, k) _S = {(4,6) ₁ , (1,11) ₂ , (4,3) ₂ }; R7 (l, k) _S = {(4,3) ₁ , (1,8) ₂ , (4,0) ₂ }
R8 (1, k) _S = {(4,0) ₁ , (1,5) ₂ , (4,9) ₂ }; R9 (1, k) _S = {(4,9) ₁ , (1,2) ₂ , (4,6) ₂ }

P-8-3 pattern (Fig. 52)

R6 (1, k) _S = {(4,6) ₁ , (1,5) ₂ , (4,9) ₂ }; R7 (l, k) _S = {(4,3) ₁ , (1,2) ₂ , (4,6) ₂ }
R8 (1, k) _S = {(4,0) ₁ , (1,11) ₂ , (4,3) ₂ }; R9 (1, k) _S = {(4,9) ₁ , (1,5) ₂ , (4,0) ₂ }

The patterns P-1 to P-8 according to the embodiment of the present invention exemplify the case of multiplexing RSs for extended four antennas in the form of FDM and TDM. However, the RS pattern illustrated above is an example, and it is also possible to multiplex a subset of resources for allocating RSs for antenna ports 6-9 in the form of CDM. For example, referring to the A-1 pattern, it can be seen that a total of six REs are used for the RSs at antenna port 6 and antenna port 8 (three at each). In this case, six REs are allocated to six REs for each of the six REs for the antenna ports 6 and 8, and RSs for the extended antenna are allocated to CDMs Can be multiplexed. In addition, the RS for the extended antenna can be multiplexed in the form of CDM using all of the REs to which the RS for the extended antenna is allocated. For example, referring to the A-1 pattern, it can be seen that a total of twelve REs are used for the RSs of the antenna ports 6 through 9 (three each). In this case, twelve RSs for each antenna port may be redundantly allocated to the twelve REs, and RSs for the extended four antennas may be multiplexed in CDM by allocating different codes or sequences for each antenna port. The multiplexing of the RS for the extended antenna by the CDM scheme can be applied to all the patterns P-1 to P-8.

In order to perform frequency dependent scheduling on each component carrier or entire component carrier as described in the present invention, RS allocation schemes for antennas 4 to 7 may be applied in the scheduling BW.

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

In this document, the embodiments of the present invention have been mainly described with reference to the data transmission / reception relationship between the terminal and the base station. The specific operation described herein as being performed by the base station may be performed by its upper node, in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. The term 'terminal' may be replaced with terms such as User Equipment (UE), Mobile Station (MS), and Mobile Subscriber Station (MSS).

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, or the like which performs the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

The present invention can be applied to a wireless communication system. The present invention can be applied to a wireless communication system supporting at least one of SC-FDMA, MC-FDMA, and OFDMA. Specifically, the present invention can be applied to a method for transmitting a reference signal in a wireless communication system in a wireless communication system.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

1 shows a structure of a radio frame used in 3GPP LTE.

2 shows a resource grid for a downlink slot.

3 shows a structure of a downlink radio frame.

4 shows a control channel allocated to a downlink subframe.

5 shows a resource unit allocated to the control channel.

6 shows an example in which the PHICH is allocated in the control area.

7 (a) and (b) illustrate a method of transmitting and receiving a multi-band radio frequency signal.

FIG. 8 illustrates a method of allocating frequencies in a multi-carrier system.

FIG. 9 illustrates a scenario in which communication is performed between one base station and a plurality of terminals in a multi-band supporting method.

10 illustrates a method of spreading and allocating RSs within a component carrier.

11 illustrates a method of spreading and allocating RSs to all component carriers.

FIG. 12-13 shows an example of assignment of RSs for antennas # 4 to # 7 to the CCE.

FIG. 14 illustrates a method of allocating RSs for antennas # 4 to # 7 among the component carriers in a TDM, FDM, or CDM scheme.

17-21 illustrate a method of multiplexing RSs for antennas 4 to 7 within a component carrier by TDM, FDM or CDM scheme.

Figure 22 illustrates a method of spreading and allocating RSs within a component carrier.

23 illustrates a method of spreading and allocating RSs to all component carriers.

24-25 shows an example of assignment of RSs for antennas 4 to 7 to PHICH.

Figs. 26 to 27 show an example of transmitting RSs of antennas 4 to 7 through the PHICH.

28 shows a flowchart for performing signaling for the RSs of the antennas 4-7.

FIGS. 29-32 illustrate a method of allocating RSs for antennas 4 to 7 by additionally using four OFDM symbols in the PDSCH.

33-34 illustrate a method of allocating RSs for antennas 4 to 7 by additionally using three OFDM symbols in the PDSCH.

35-42 illustrate a method of allocating RSs for antennas 4 to 7 by additionally using two OFDM symbols in the PDSCH.

43 to 44 illustrate a method of allocating RSs for antennas 4 to 7 by additionally using one OFDM symbol in the PDSCH.

FIG. 45 illustrates a method of allocating RSs for antennas 4 to 7 using OFDM symbols allocated to RSs for FMFs 0 to 3 in the PDSCH.

46 shows a pattern of RS for antenna port 5 in a subframe.

47-52 illustrate a method of allocating RSs for antennas 4 to 7 by reusing the RS pattern of antenna port 5.

Claims (20)

A method for transmitting a reference signal in a wireless communication system, Generating a subframe including a plurality of PHICH (Physical Hybrid-ARQ Indicator CHannel) groups; Assigning a reference signal to one or more specific PHICH groups; And And transmitting the sub-frame, Wherein the reference signal is a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a DM-RS (DeModulation Reference Signal) for the fifth to eighth antennas among the eight antennas. The method according to claim 1, Wherein the at least one particular PHICH group is selected to be evenly distributed within the system band. The method according to claim 1, Wherein the at least one specific PHICH group is determined by selecting a physical index of a PHICH group or a physical index of a REG constituting a PHICH group at equal intervals. The method according to claim 1, Wherein the reference signal is allocated using a part of resources of the specific PHICH group. The method according to claim 1, Wherein the reference signal is allocated using a continuous PHICH group or a continuous REG. delete The method according to claim 1, Further comprising the step of transmitting information for identifying the PHICH resource to which the reference signal is allocated. A reference signal processing method in a wireless communication system, Receiving information for identifying a PHICH resource to which a reference signal is assigned; Receiving a sub-frame including a plurality of PHICH (Physical Hybrid-ARQ Indicator CHannel) groups; Extracting a reference signal from one or more specific PHICH groups based on the control information; And Estimating a channel using the reference signal, Wherein the reference signal is a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a DM-RS (DeModulation Reference Signal) for the fifth to eighth antennas among the eight antennas. A method for transmitting a reference signal in a wireless communication system, Generating a subframe including a PDCCH search space made up of a plurality of CCEs (Control Channel Elements); Assigning a reference signal in the PDCCH search space; And And transmitting the sub-frame. 10. The method of claim 9, Wherein the reference signal is allocated in a CCE set composed of a predetermined number of CCEs. 10. The method of claim 9, Wherein the reference signal is allocated to a UE-common search space that is allowed to search for all terminals in the cell in the PDCCH search space. 12. The method of claim 11, Wherein the reference signal is allocated in a remaining space other than the CCE reserved for a predetermined purpose among the UE-common search space. 13. The method of claim 12, Wherein the CCE reserved for the predetermined purpose is associated with a RACH (Random Access CHannel). 12. The method of claim 11, Wherein the reference signal for the first antenna group is allocated to the first UE common search space and the reference signal for the second antenna group is allocated to the second UE common search space. 15. The method of claim 14, Wherein the first antenna group includes first to fourth antennas among eight antennas, and the first antenna group includes fifth to eighth antennas among the eight antennas. 10. The method of claim 9, Wherein the reference signal is allocated to a UE-specific search space that is allowed to search only for a specific UE in the PDCCH search space. 17. The method of claim 16, Wherein the reference signal is allocated to a first or last CCE of the UE-specific search space and one or more CCEs continuous to the CCE. 17. The method of claim 16, Wherein the reference signal is allocated to a plurality of CCEs located at equal intervals in the terminal-specific search space. 10. The method of claim 9, The reference signal is a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a DM-RS (DeModulation Reference Signal) for the fifth to eighth antennas among eight antennas. Signal transmission method. A reference signal processing method in a wireless communication system, Receiving a subframe including a PDCCH search space including a plurality of CCEs (Control Channel Elements); Checking a specific CCE to which a reference signal is allocated in the PDCCH search space; Extracting a reference signal from the specific CCE; And And estimating a channel using the reference signal.

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